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 A172645 #8 Feb 03 2021 21:40:45 %S A172645 1,3,31,2371,1084851,3680774301,91358224634433,17470072106054582211, %T A172645 26088526624958727703324771,310419652143758898175543447421953, %U A172645 29785621316391113552729016416250323294253 %N A172645 Number of n X n 0..2 arrays with row sums n and column sums n. %H A172645 R. H. Hardin, <a href="/A172645/b172645.txt">Table of n, a(n) for n=1..14</a> %Y A172645 Main diagonal of A334549. %K A172645 nonn %O A172645 1,2 %A A172645 _R. H. Hardin_, Feb 06 2010