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 A140981 #9 Feb 21 2024 01:19:25 %S A140981 1,1,4,7,34,109,1044,8303,274668,7451736,1018997864 %N A140981 Number of graphs with n vertices that have an even determinant for the adjacency matrix. %F A140981 a(n) = A000088(n) - A141040(n/2) for n even, a(n) = A000088(n) for n odd. %Y A140981 Cf. A000088, A103869, A141040. %K A140981 more,nonn %O A140981 1,3 %A A140981 _Tanya Khovanova_, Aug 18 2008 %E A140981 a(8)-a(10) from _Andrew Howroyd_, Nov 04 2017 %E A140981 a(11) from A000088 added by _Max Alekseyev_, Feb 20 2024