\documentclass[12pt,reqno]{article} \usepackage[usenames]{color} \usepackage{amssymb} \usepackage{graphicx} \usepackage{amscd} \usepackage[colorlinks=true, linkcolor=webgreen, filecolor=webbrown, citecolor=webgreen]{hyperref} \definecolor{webgreen}{rgb}{0,.5,0} \definecolor{webbrown}{rgb}{.6,0,0} \usepackage{color} \usepackage{fullpage} \usepackage{float} \usepackage{psfig} \usepackage{graphics,amsmath,amssymb} \usepackage{amsthm} \usepackage{amsfonts} \usepackage{latexsym} \usepackage{epsf} \setlength{\textwidth}{6.5in} \setlength{\oddsidemargin}{.1in} \setlength{\evensidemargin}{.1in} \setlength{\topmargin}{-.5in} \setlength{\textheight}{8.9in} \newcommand{\seqnum}[1]{\href{http://oeis.org/#1}{\underline{#1}}} \begin{document} \begin{center} \epsfxsize=4in \leavevmode\epsffile{logo129.eps} \end{center} \theoremstyle{plain} \newtheorem{theorem}{Theorem} \newtheorem{corollary}[theorem]{Corollary} \newtheorem{lemma}[theorem]{Lemma} \newtheorem{proposition}[theorem]{Proposition} \theoremstyle{definition} \newtheorem{definition}[theorem]{Definition} \newtheorem{example}[theorem]{Example} \newtheorem{conjecture}[theorem]{Conjecture} \theoremstyle{remark} \newtheorem{remark}[theorem]{Remark} \begin{center} \vskip 1cm{\LARGE\bf On Some Magnified Fibonacci Numbers \\ \vskip .12in Modulo a Lucas Number} \\ \vskip 1cm \large Ram Krishna Pandey \\ Department of Mathematics\\ Indian Institute of Technology Patna \\ Patliputra Colony, Patna - 800013\\ India \\ \href{mailto:ram@iitp.ac.in}{\tt ram@iitp.ac.in} \end{center} \vskip .2in \begin{abstract} Let, as usual, $F_n$ and $L_n$ denote the $n$th Fibonacci number and the $n$th Lucas number, respectively. In this paper, we consider the Fibonacci numbers $F_2, F_3, \ldots, F_{t}.$ Let $n \geq 1$ be an integer such that $4n+2 \leq t \leq 4n+5$ and $m = F_{2n+2} + F_{2n+4} = L_{2n+3}.$ We prove that the integers $F_2 F_{2n+2}, F_3 F_{2n+2}, \ldots, F_{t} F_{2n+2}$ modulo $m$ all belong to the interval $[F_{2n+1}, 3F_{2n+2}].$ Furthermore, the endpoints of the interval $[F_{2n+1}, 3F_{2n+2}]$ are obtained only by the integers $F_4 F_{2n+2}$ and $F_{4n+2} F_{2n+2}$, respectively. \end{abstract} \section{Introduction} Let $m_1, m_2, \ldots $ be positive integers. Cusick and Pomerance \cite{cusickpom} discuss the quantity $\kappa$ where \[\kappa := \sup_{x\in(0,1)}\min_{i}\|xm_{i}\|.\] Here, for $x \in \mathbb{R}$, $\|x\|$ is distance to the nearest integer. Observe that if we have a finite number of integers $m_1, m_2, \ldots, m_n$ and \[\kappa_1 := \displaystyle\max_{\stackrel{m = m_j + m_l}{1 \leq k \leq m/2}} \ \frac{1}{m}\min_{i}|km_{i}|_m,\] where $ |x|_m $ denotes the absolute value of the absolutely least remainder of $x$ mod $m$, then by a remark of Haralambis \cite{har} we have that $\kappa = \kappa_1$. The quantity $\kappa$ has become an important quantity now; it is involved in the well-known {\em Lonely Runner conjecture}. This conjecture, due to Bienia et al.\ \cite{bienia}, is stated as follows: \begin{quote} Suppose $n$ runners having nonzero distinct constant speeds run laps on a unit-length circular track. Then there is a time at which all the $n$ runners are simultaneously at least $1/(n+1)$ units from their common starting point. \end{quote} The original form of this conjecture, as given by Wills \cite{wills} and Cusick \cite{cusick}, is as follows: \begin{quote} Suppose $m_1, m_2, \ldots, m_n$ be $n$ positive integers. Then $\kappa \geq 1/(n+1).$ \end{quote} This is an interpretation also due to Liu and Zhu \cite{liuzhu}. In the present paper we show that if the integers $m_1, m_2, \ldots, m_n$ in the definition of $\kappa$ are $F_2, F_3, \ldots, F_t$ and $n \geq 1$ be an integer such that $4n+2 \leq t \leq 4n+5$, then \[\kappa \geq \frac{F_{2n+1}}{F_{2n+2}+F_{2n+4}}.\] This also confirms the lonely runner conjecture in the case where the speeds of the runners are $F_2, F_3, \ldots, F_t$. \section {Main Results} Let $M = \{F_2, F_3, \ldots, F_t\}$. Let $n \geq 1$ be an integer such that $4n+2 \leq t \leq 4n+5$ and $m = F_{2n+2} + F_{2n+4} = L_{2n+3}.$ The above bound about $\kappa$ may be obtained using Theorem \ref{t1} and $\kappa_1.$ The lonely runner conjecture is also satisfied in the special case $n=0$. In this special case the set of speeds may be $\{F_2\}$, $\{F_2, F_3\}$, $\{F_2, F_3, F_4\}$, and $\{F_2, F_3,F_4,F_5\}$. Taking $x = \frac{1}{2}$, $\frac{1}{3}$, $\frac{1}{4}$, and $\frac{1}{4}$ in the definition of $\kappa$ for the sets $\{F_2\}$, $\{F_2, F_3\}$, $\{F_2, F_3, F_4\}$, and $\{F_2, F_3,F_4,F_5\}$, respectively, we see that the lonely runner conjecture is satisfied. In this section, we use the following identities and these identities may be found in Koshy \cite{koshy}. \begin{enumerate} \item Cassini's identity: $F^2_n - F_{n+1}F_{n-1} = (-1)^{n-1}$. \item $F^2_n + F^2_{n+1} = F_{2n+1}$. \item d'Ocagne's identity: $F_m F_{n+1} - F_{m+1} F_n = (-1)^n F_{m-n}$. \item $F_{2n} = \sum_{i=0}^{n-1} F_{2i+1}$. \item $F_{2n+1}-1 = \sum_{i=1}^{n} F_{2i}$. \end{enumerate} \begin{lemma}\label{f1} \begin{itemize} \item [(a)] $F_2 F_{2n+2} \equiv F_{4n+5}F_{2n+2} \pmod m$. \item [(b)] $F_2 F_{2n+2} \equiv - F_{4n+4}F_{2n+2} \pmod m$. \item [(c)] $F_3 F_{2n+2} \equiv F_{4n+3}F_{2n+2} \pmod m$. \item [(d)] $F_4 F_{2n+2} \equiv -F_{4n+2}F_{2n+2} \pmod m$. \end{itemize} \end{lemma} \begin{proof} \begin{itemize} \item [(a)] We have \begin{eqnarray*} m F_{2n+2} &=& (F_{2n+2} + F_{2n+4})F_{2n+2}\\ &=& F^2_{2n+2} + F_{2n+4}F_{2n+2}\\ &=& F^2_{2n+2} + (F_{2n+3} + F_{2n+2})(F_{2n+3} - F_{2n+1})\\ &=& F^2_{2n+2} + F^2_{2n+3} + F_{2n+3}F_{2n+2} - F_{2n+3}F_{2n+1} - F_{2n+2}F_{2n+1}\\ &=& F^2_{2n+2} + F^2_{2n+3} + (F_{2n+2} + F_{2n+1})F_{2n+2} - F_{2n+3}F_{2n+1} - F_{2n+2}F_{2n+1}\\ &=& F^2_{2n+2} + F^2_{2n+3} + F^2_{2n+2} - F_{2n+3}F_{2n+1}\\ &=& F^2_{2n+2} + F^2_{2n+3} + (-1)^{2n+1} \quad \left(\text {using Cassini's identity}\right)\\ &=& F_{4n+5} - 1 \quad \left(\text {using the identity} F^2_n + F^2_{n+1} = F_{2n+1}\right). \end{eqnarray*} Hence we get \[F_{4n+5}F_{2n+2} = (1+ m F_{2n+2})F_{2n+2} \equiv F_{2n+2} = F_{2}F_{2n+2} \pmod m.\] \item [(b)] We have \begin{eqnarray*} F_{2}F_{2n+2} &\equiv& F_{4n+5}F_{2n+2} \pmod m \quad \left(\text {by (a)}\right)\\ &=& (F_{4n+6} - F_{4n+4})F_{2n+2}\\ &=& F_{4n+6}F_{2n+2} - F_{4n+4}F_{2n+2}\\ &=& (L_{2n+3}F_{2n+3})F_{2n+2} - F_{4n+4}F_{2n+2} \quad \left(\text{since } L_n F_n = F_{2n}\right)\\ &\equiv& - F_{4n+4}F_{2n+2} \pmod m \quad \left(\text{as } m = L_{2n+3}\right). \end{eqnarray*} \item [(c)] $F_3 F_{2n+2} = (F_2 + F_1)F_{2n+2} \equiv (F_{4n+5} -F_{4n+4})F_{2n+2} \equiv F_{4n+3}F_{2n+2} \pmod m$. \item [(d)] $F_4 F_{2n+2} = (F_3 + F_2)F_{2n+2} \equiv (F_{4n+3} -F_{4n+4})F_{2n+2} \equiv - F_{4n+2}F_{2n+2} \pmod m$. \end{itemize} \end{proof} \begin{lemma} $F_{r+5} F_{2n+2} = (F_{r+4} + F_{r+3})F_{2n+2} \equiv \epsilon F_{4n+1-r} F_{2n+2} \pmod m$ for each $0 \leq r \leq 2n-2,$ where \[ \epsilon = \left\{% \begin{array}{ll} +1, & \text{if $r$ is even;} \\ -1, & \text{if $r$ is odd.} \\ \end{array}% \right. \] \end{lemma} \begin{proof} Using the recurrence relation $F_{n+1} = F_{n} + F_{n-1}$ for $n \geq 1$ and Lemma \ref{f1}, the proof follows by induction on $r$. \end{proof} Thus in order to examine the integers $F_2 F_{2n+2}, F_3 F_{2n+2}, \ldots, F_{4n+5} F_{2n+2}$ modulo $m$, it is sufficient to examine only the integers $F_2 F_{2n+2}, F_3 F_{2n+2}, \ldots, F_{2n+3} F_{2n+2}$ modulo $m$. \begin{lemma}\label{f2} \begin{itemize} \item [(a)] $F_2 F_{2n+2} \equiv F_{2n+2} \pmod m$. \item [(b)] $F_3 F_{2n+2} \equiv -F_{2n+3} \pmod m$. \item [(c)] $F_4 F_{2n+2} \equiv -F_{2n+1} \pmod m$. \item [(d)] $F_5 F_{2n+2} \equiv 2F_{2n+2} - F_{2n+1} \pmod m$. \end{itemize} \end{lemma} \begin{proof} \begin{itemize} \item [(a)] $F_2 F_{2n+2} \equiv F_{2n+2} \pmod m$ (as $F_2 = 1$). \item [(b)] $F_3 F_{2n+2} = 2F_{2n+2} \equiv - (F_{2n+1}+F_{2n+2}) = -F_{2n+3} \pmod m$. \item [(c)] $F_4 F_{2n+2} = (F_2+F_3)F_{2n+2} \equiv F_{2n+2} - F_{2n+3} = -F_{2n+1} \pmod m$. \item [(d)] $F_5 F_{2n+2} = 5F_{2n+2} \equiv 2F_{2n+2} - F_{2n+1} \pmod m$. \end{itemize} \end{proof} We observe that in all above four congruences if $R$ is the remainder then we have, $F_{2n+1} \leq |R| \leq \frac{m}{2}$, i.e., we have that the positive remainder is always in the interval $[F_{2n+1}, 3F_{2n+2}]$. Inductively, we can prove that \[F_{2n+3-k} = F_{2n-1-k}F_{5} + F_{2n-2-k}F_{4}\] for each $0 \leq k \leq 2n-3$. Hence we have \begin{eqnarray*} F_{2n+3-k}F_{2n+2} &=& (F_{2n-1-k}F_{5} + F_{2n-2-k}F_{4})F_{2n+2}\\ &\equiv& F_{2n-1-k}(2F_{2n+2}-F_{2n+1}) - F_{2n-2-k}F_{2n+1}\pmod m \quad \left(\text{using (c), (d) of Lemma \ref{f2}}\right)\\ &=& F_{2n-1-k}F_{2n+2} + F_{2n-1-k}(F_{2n+1} + F_{2n}) - F_{2n-1-k}F_{2n+1} - F_{2n-2-k}F_{2n+1}\\ &=& F_{2n-1-k}F_{2n+2} + F_{2n-1-k}F_{2n} - F_{2n-2-k}F_{2n+1}\\ &=& F_{2n-1-k}F_{2n+2} + (-1)^{2n-2-k}F_{2+k} \quad \left(\text {using d'Ocagne's identity}\right). \end{eqnarray*} Thus we get \begin{equation} F_{2n+3-k}F_{2n+2} \equiv F_{2n-1-k}F_{2n+2} + \epsilon F_{2+k} \pmod m, \hfill \ldots \label{star} \end{equation} where \[ \epsilon = \left\{% \begin{array}{ll} +1, & \text{if $k$ is even;} \\ -1, & \text{if $k$ is odd.} \\ \end{array}% \right. \] \begin{lemma}\label{f3} Let $R_k = F_{2n-1-k}F_{2n+2} + \epsilon F_{2+k}$ for each $0 \leq k \leq 2n-3$, where \[ \epsilon = \left\{% \begin{array}{ll} +1, & \text{if $k$ is even;} \\ -1, & \text{if $k$ is odd.} \\ \end{array}% \right. \] Then $F_{2n+1} < |R_k|_m < \frac{m}{2}$. \end{lemma} \begin{proof} We partition the set $\{0,1,2, \ldots, 2n-3\}$ into the sets $A_2, A_3, A_4,$ and $A_5$ where \[A_i = \left\{2n-1-i-4t : 0 \leq t \leq \left\lfloor \frac{2n-1-i}{4} \right\rfloor\right\},\] for each $2 \leq i \leq 5.$ Notice that \[ \epsilon = \left\{% \begin{array}{ll} +1, & \text{if $k \in A_3 \cup A_5$;} \\ -1, & \text{if $k \in A_2 \cup A_4$.} \\ \end{array}% \right. \] We consider the following cases: \medskip {\bf Case I:} ($k \in A_2)$. Clearly (\ref{star}) implies that \[F_{6+4t}F_{2n+2} \equiv F_{2+4t}F_{2n+2} - F_{2n-1-4t} \pmod m.\] $t =0 \Rightarrow F_{6}F_{2n+2} \equiv F_{2}F_{2n+2} - F_{2n-1} \equiv F_{2n+2} - F_{2n-1} \pmod m.$ Observe that $F_{2n+1} < F_{2n+2} - F_{2n-1} < m/2.$ $t =1 \Rightarrow F_{10}F_{2n+2} \equiv F_{6}F_{2n+2} - F_{2n-5} \equiv F_{2n+2} - F_{2n-1} - F_{2n-5}\pmod m.$ Observe that $F_{2n+1} < F_{2n+2} - F_{2n-1} - F_{2n-5} < m/2.$ Inductively, we let $t = \lfloor \frac{2n-3}{4} \rfloor$. In this case $k = 1$ or $k = 3$ depending on $n$ is even or odd. If $k =1$, then we have $F_{2n+2}F_{2n+2} \equiv F_{2n-2}F_{2n+2} - F_{3} \equiv F_{2n+2} - (F_{2n-1} + F_{2n-5} + \dots + F_3) \pmod m.$ Observe that $F_{2n+1} < F_{2n+2} - (F_{2n-1} + F_{2n-5} + \dots + F_3) < m/2$ as we have the identity $F_{2n} = \sum_{i=0}^{n-1} F_{2i+1}$. If $k =3$, then we have $F_{2n}F_{2n+2} \equiv F_{2n-4}F_{2n+2} - F_{5} \equiv F_{2n+2} - (F_{2n-1} + F_{2n-5} + \dots + F_5) \pmod m.$ Observe that $F_{2n+1} < F_{2n+2} - (F_{2n-1} + F_{2n-5} + \dots + F_5) < m/2$ as we have the identity $F_{2n} = \sum_{i=0}^{n-1} F_{2i+1}$. \medskip {\bf Case II:} ($k \in A_3$). Clearly (\ref{star}) implies that \[F_{7+4t}F_{2n+2} \equiv F_{3+4t}F_{2n+2} + F_{2n-2-4t} \pmod m.\] $t =0 \Rightarrow F_{7}F_{2n+2} \equiv F_{3}F_{2n+2} + F_{2n-2} \equiv -F_{2n+3} + F_{2n-2} \pmod m.$ Observe that $F_{2n+1} < |-F_{2n+3} + F_{2n-2}| < m/2.$ $t =1 \Rightarrow F_{11}F_{2n+2} \equiv F_{7}F_{2n+2} + F_{2n-6} \equiv -F_{2n+3} + F_{2n-2} + F_{2n-6}\pmod m.$ Observe that $F_{2n+1} < |-F_{2n+3} + F_{2n-2} + F_{2n-6}| < m/2.$ Inductively, we let $t = \lfloor \frac{2n-4}{4} \rfloor$. In this case $k = 0$ or $k = 2$ depending on $n$ is even or odd. If $k =0$, then we have $F_{2n+3}F_{2n+2} \equiv F_{2n-1}F_{2n+2} + F_{2} \equiv -F_{2n+3} + (F_{2n-2} + F_{2n-6} + \dots + F_2) \pmod m.$ Observe that $F_{2n+1} < |-F_{2n+3} + (F_{2n-2} + F_{2n-6} + \dots + F_2)| < m/2$ as we have $F_{2n+3} - (F_{2n-2} + F_{2n-6} + \dots + F_2) = F_{2n+1} + F_{2n+2} - (F_{2n-2} + F_{2n-6} + \dots + F_2)$ and the identity $F_{2n+1}-1 = \sum_{i=1}^{n} F_{2i}$ If $k =2$, the result follows from the above case $k=0$. \medskip {\bf Case III:} ($k \in A_4$). Clearly (\ref{star}) implies that \[F_{8+4t}F_{2n+2} \equiv F_{4+4t}F_{2n+2} - F_{2n-3-4t} \pmod m.\] $t =0 \Rightarrow F_{8}F_{2n+2} \equiv F_{4}F_{2n+2} - F_{2n-3} \equiv -F_{2n+1} - F_{2n-3} \pmod m.$ Observe that $F_{2n+1} < F_{2n+1} + F_{2n-3} < m/2.$ $t =1 \Rightarrow F_{12}F_{2n+2} \equiv F_{8}F_{2n+2} - F_{2n-7} \equiv -(F_{2n+1} + F_{2n-3} + F_{2n-7})\pmod m.$ Observe that $F_{2n+1} < F_{2n+1} + F_{2n-3} + F_{2n-7} < m/2.$ Inductively, we let $t = \lfloor \frac{2n-5}{4} \rfloor$. In this case $k = 1$ or $k = 3$ depending on $n$ is odd or even. If $k =1$, then we have $F_{2n+2}F_{2n+2} \equiv F_{2n-2}F_{2n+2} - F_{3} \equiv -(F_{2n+1} + F_{2n-3} + F_{2n-7}+\ldots + F_3) \pmod m.$ Observe that $F_{2n+1} + F_{2n-3} + F_{2n-7}+\ldots + F_3 < m/2$ as we have the identity $F_{2n} = \sum_{i=0}^{n-1} F_{2i+1}.$ If $k =3$. It follows from the above case $k=1$. \medskip {\bf Case IV:} ($k \in A_5$) Clearly (\ref{star}) implies that \[F_{9+4t}F_{2n+2} \equiv F_{5+4t}F_{2n+2} + F_{2n-4-4t} \pmod m.\] $t =0 \Rightarrow F_{9}F_{2n+2} \equiv F_{5}F_{2n+2} + F_{2n-4} \equiv 2F_{2n+2} - F_{2n+1}+ F_{2n-4} \pmod m.$ Observe that $F_{2n+1} < 2F_{2n+2} - F_{2n+1}+ F_{2n-4} < m/2.$ $t =1 \Rightarrow F_{13}F_{2n+2} \equiv F_{9}F_{2n+2} + F_{2n-8} \equiv 2F_{2n+2} - F_{2n+1}+ F_{2n-4} + F_{2n-8} \pmod m.$ Observe that $F_{2n+1} < 2F_{2n+2} - F_{2n+1}+ F_{2n-4} + F_{2n-8} < m/2.$ Inductively, we let $t = \lfloor \frac{2n-6}{4} \rfloor$. In this case $k = 0$ or $k = 2$ depending on $n$ is odd or even. If $k =0$, then we have $F_{2n+3}F_{2n+2} \equiv F_{2n-1}F_{2n+2} + F_{2} \equiv 2F_{2n+2} - F_{2n+1}+ (F_{2n-4} + F_{2n-8} + \ldots + F_2) \pmod m.$ Observe that $F_{2n+1} < 2F_{2n+2} - F_{2n+1}+ (F_{2n-4} + F_{2n-8} + \ldots + F_2) < m/2$ as we have $2F_{2n+2} - F_{2n+1}+ (F_{2n-4} + F_{2n-8} + \ldots + F_2) = F_{2n+2} + F_{2n}+ (F_{2n-4} + F_{2n-8} + \ldots + F_2) < F_{2n+2} + F_{2n+1} - 1 < m/2$ using the identity $F_{2n+1}-1 = \sum_{i=1}^{n} F_{2i}$ If $k =2$. It follows from the above case $k=0$. \end{proof} \begin{theorem} \label{t1} Let $F_2, F_3, \ldots, F_{t}$ be the Fibonacci numbers and let $n \geq 1$ be an integer such that $4n+2 \leq t \leq 4n+5$ and $m = F_{2n+2} + F_{2n+4} = L_{2n+3}.$ Then the integers $F_2 F_{2n+2}, F_3 F_{2n+2}, \ldots, F_{t} F_{2n+2}$ modulo $m$ all belong to the interval $[F_{2n+1}, 3F_{2n+2}].$ Moreover, both the endpoints of the interval $[F_{2n+1}, 3F_{2n+2}]$ are obtained only by the integers $F_4 F_{2n+2}$ and $F_{4n+2} F_{2n+2}$, respectively. \end{theorem} \begin{proof} Lemma \ref{f2} and Lemma \ref{f3} together prove the theorem. \end{proof} \section {Acknowledgements} The author wishes to thank to the referees for their useful comments. \begin{thebibliography}{5} \bibitem {betkewills} U. Betke and J. M. Wills, Untere Schranken f{\"u}r zwei diophantische Approximations-Functionen, {\it Monatsh. Math.} \textbf{76} (1972), 214--217. \bibitem {bienia} W. Bienia, L. Goddyn, P. Gvozdjak, A. Sebo, and M. Tarsi, Flows, view-obstructions and the lonely runner, {\it J. Combin. Theory Ser. B} \textbf{72} (1998), 1--9. \bibitem {cusick} T. W. Cusick, View-obstruction problems in $n$-dimensional geometry, {\it J. Combin. Theory Ser. A} \textbf{16} (1974), 1--11. \bibitem {cusickpom} T. W. Cusick and C. Pomerance, View-obstruction problems III, {\it J. Number Theory} \textbf{19} (1984), 131--139. \bibitem {har} N. M. Haralambis, Sets of integers with missing differences, {\it J. Combin. Theory Ser. A} \textbf{23} (1977), 22--33. \bibitem {koshy} T. Koshy, {\it Fibonacci and Lucas Numbers with Applications}, Wiley, 2001. \bibitem {liuzhu} D. D.-F. Liu and X. Zhu, Fractional chromatic number for distance graphs with large clique size, {\it J. Graph Theory} \textbf{47} (2004), 129--146. \bibitem {wills} J. M. Wills, Zwei S{\"a}tze {\"u}ber inhomogene diophantische Approximation von Irrationalzahlen, {\it Monatsh. Math.} {\bf 71} (1967), 263--269. \end{thebibliography} \bigskip \hrule \bigskip \noindent 2010 {\it Mathematics Subject Classification}: Primary 11B39. \noindent \emph{Keywords: } Fibonacci numbers, Lucas numbers, congruences. \bigskip \hrule \bigskip \noindent (Concerned with sequence \seqnum{A000045}.) \bigskip \hrule \bigskip \vspace*{+.1in} \noindent Received September 28 2012; revised version received January 21 2013. Published in {\it Journal of Integer Sequences}, January 26 2013. \bigskip \hrule \bigskip \noindent Return to \htmladdnormallink{Journal of Integer Sequences home page}{http://www.cs.uwaterloo.ca/journals/JIS/}. \vskip .1in \end{document} .