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 A118993 #6 Jun 18 2025 18:02:41 %S A118993 2,4,64,832,23808,1725952,268435456,64638447616,33770336417792 %N A118993 Number of real n X n symmetric (+1,-1) matrices with nonzero permanent. %Y A118993 Cf. A086899, A118988, A118991, A118992, A118995, A118999, A119001, A119010. %K A118993 nonn,more %O A118993 1,1 %A A118993 _Giovanni Resta_, May 08 2006 %E A118993 a(8)-a(9) from _Max Alekseyev_, Jun 18 2025