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 A118999 #7 Jun 19 2025 00:24:51 %S A118999 1,0,32,240,11904,533568,134217728,22741568512,16885168208896 %N A118999 Number of real n X n symmetric (+1,-1) matrices with negative permanent. %F A118999 a(n) = A118993(n) - A118995(n). For odd n, a(n) = A118995(n) = A118993(n)/2. - _Max Alekseyev_, Jun 18 2025 %Y A118999 Cf. A118988, A118997, A118999, A118993, A118994, A118995, A119001, A119010. %K A118999 nonn,more %O A118999 1,3 %A A118999 _Giovanni Resta_, May 08 2006 %E A118999 a(1) corrected and a(8)-a(9) added by _Max Alekseyev_, Jun 18 2025