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 A169776 #13 Jul 01 2017 23:00:09 %S A169776 2,0,0,2,10,12,22,60,76,160,292,652,1148,2600,3870,9152,13710,32792, %T A169776 48112,116624,171732,428064,589842,1496508,2069766,5348640,7164172, %U A169776 18742712,25160796,66758832,86664762,232553036,302742306,821495496,1044549008 %N A169776 Number of geometrically distinct open knight's tours of a 3 X n chessboard that have twofold symmetry. %D A169776 D. E. Knuth, Long and skinny knight's tours, in Selected Papers on Fun and Games, to appear, 2010. %H A169776 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 A169776 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 A169776 D. E. Knuth <a href="/A169770/a169770.txt">Generating functions for A169770-A169777 and A169696.</a> %F A169776 A169776(n) = (A169773(n) + A169774(n) + A169775(n))/2. %Y A169776 Cf. A070030, A169696, A169764-A169777. %K A169776 nonn %O A169776 4,1 %A A169776 _N. J. A. Sloane_, May 10 2010, based on a communication from _Don Knuth_, Apr 28 2010 %E A169776 a(31)-a(38) from _Andrew Howroyd_, Jul 01 2017