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 A089957 #26 Jan 08 2017 12:52:00 %S A089957 1,20,400,1862,9825,53516,311642,2018993,12150635,69284509,382383387, %T A089957 1994236773 %N A089957 Number of chess positions that can be obtained in exactly one way in n plies. %C A089957 Definition: position = position with castling and en passant information, diagram = position without castling and en passant information. %C A089957 The positions are taken from the sets that are counted in A083276. %H A089957 F. Labelle, <a href="http://www.cs.berkeley.edu/~flab/chess/statistics-positions.html">Statistics on chess positions</a> %H A089957 P. Österlund, <a href="http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=508645&t=41032">Computation of a(11)</a>. %H A089957 <a href="/index/Ch#chess">Index entries for sequences related to number of chess games</a> %Y A089957 Cf. A083276, A090051. %K A089957 nonn,hard,more,fini %O A089957 0,2 %A A089957 _François Labelle_, Jan 12 2004 %E A089957 a(9) from _François Labelle_, Mar 09 2004 %E A089957 a(10) from _Arkadiusz Wesolowski_, Jan 04 2012 %E A089957 a(11) from Peter Österlund on Feb 22 2013, verified by _François Labelle_ on Jan 08 2017