This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A169771 #13 Jul 23 2017 16:37:35 %S A169771 2,0,0,52,224,520,1616,10320,37024,125120,441200,1798576,6327472, %T A169771 22985504,81178008,301420176,1057619944,3818476576,13412523392, %U A169771 48285742208,168992600680,602349395456,2106360581920,7471875943776,26073917403304,92017860990176,320713651212384 %N A169771 Number of open knight's tour diagrams of a 3 X n chessboard that have "type F": the endpoints occur in different columns and agree in color with the cells in the nearest corner. %D A169771 D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010. %H A169771 Seiichi Manyama, <a href="/A169771/b169771.txt">Table of n, a(n) for n = 4..1000</a> %H A169771 George Jelliss, <a href="http://www.mayhematics.com/t/oa.htm">Open knight's tours of three-rank boards</a>, Knight's Tour Notes, note 3a (21 October 2000). %H A169771 George Jelliss, <a href="http://www.mayhematics.com/t/ob.htm">Closed knight's tours of three-rank boards</a>, Knight's Tour Notes, note 3b (21 October 2000). %H A169771 D. E. Knuth <a href="/A169770/a169770.txt">Generating functions for A169770-A169777 and A169696.</a> %F A169771 Asymptotic value: 0.02789*3.45059^n. %Y A169771 Cf. A070030, A169696, A169764-A169777. %K A169771 nonn %O A169771 4,1 %A A169771 _N. J. A. Sloane_, May 10 2010, based on a communication from _Don Knuth_, Apr 28 2010