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 A086879 #3 Mar 30 2012 17:29:07 %S A086879 1,4,36,576,18880,1208320,155553792,39821770752,20417644331008, %T A086879 20907667794952192,42834024773286100992,175448165471379869663232, %U A086879 1437398154830976169705209856,23550331368750713564450158280704 %N A086879 Number of symmetric singular n X n matrices over GF(2). %F A086879 a(n) = 2^(n*(n+1)/2) - A086812(n). %Y A086879 Cf. A086812. %K A086879 nonn %O A086879 1,2 %A A086879 Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 16 2003 %E A086879 More terms from _Ray Chandler_, Sep 19 2003