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 A069344 #8 Apr 07 2021 18:51:03 %S A069344 1,3,19,246,6486,346550,37410572,8142026722,3567024626500, %T A069344 3142034178023610 %N A069344 Number of n X n symmetric binary arrays with path of adjacent 1's from upper right corner to lower left corner. %Y A069344 Cf. n X m A069325-A069342, n X n non-symmetric A069343. %K A069344 nonn %O A069344 1,2 %A A069344 _R. H. Hardin_, Mar 16 2002