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 A169770 #12 Jul 23 2017 16:37:25 %S A169770 4,0,0,0,80,40,368,352,5296,3744,48656,40208,523808,415488,5270976, %T A169770 4333504,54215264,44497728,551297184,458337984,5613555008,4691821600, %U A169770 56981627840,47988689152,577641089664,489273948160,5845628996352 %N A169770 Number of open knight's tour diagrams of a 3 X n chessboard that have "type X": both endpoints occur in the same column. %D A169770 D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010. %H A169770 Seiichi Manyama, <a href="/A169770/b169770.txt">Table of n, a(n) for n = 4..1000</a> %H A169770 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 A169770 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 A169770 D. E. Knuth <a href="/A169770/a169770.txt">Generating functions for A169770-A169777 and A169696.</a> %F A169770 Asymptotic value 0.000169*n*3.11949^n when n is even, 0.0000526*n*3.11949^n when n is odd. %Y A169770 Cf. A070030, A169696, A169764-A169777. %K A169770 nonn %O A169770 4,1 %A A169770 _N. J. A. Sloane_, May 10 2010, based on a communication from _Don Knuth_, Apr 28 2010