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 A258110 #14 May 27 2015 15:44:29 %S A258110 0,0,0,0,3,212,10592,449977,17727425,680781219,26046238416, %T A258110 1001222256515,38764377926857,1511202832516487 %N A258110 Number of Mirror Chess games that end in checkmate after exactly n moves. %H A258110 J. Loy, <a href="https://web.archive.org/web/20130809093739/http://jimloy.com/chess/mirror1.htm">A Mirror Chess Problem</a> %e A258110 a(4) = 3 because of these checkmates: %e A258110 1. c4 c5 2. Qa4 Qa5 3. Qc6 Qc3 4. Qxc8# %e A258110 1. d4 d5 2. Qd3 Qd6 3. Qh3 Qh6 4. Qxc8# %e A258110 1. d4 d5 2. Qd3 Qd6 3. Qf5 Qf4 4. Qxc8# %Y A258110 Cf. A079485, A136257. %K A258110 nonn,hard,more,fini %O A258110 0,5 %A A258110 _Jeremy Gardiner_, May 20 2015 %E A258110 a(5)-a(13) from _François Labelle_, May 25 2015