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 A172540 #6 Apr 11 2017 16:03:29 %S A172540 0,0,0,0,0,0,0,0,1,3628800,158815387962000,9254768770160124288000, %T A172540 769237071909157579108571190000, %U A172540 96986285294151066094112970262797953280,19092174983817380047229162651397270697765056000 %N A172540 Number of n X n 0..1 arrays with row sums 9 and column sums 9. %H A172540 R. H. Hardin, <a href="/A172540/b172540.txt">Table of n, a(n) for n=1..20</a> %Y A172540 Column k=9 of A008300. %K A172540 nonn %O A172540 1,10 %A A172540 _R. H. Hardin_, Feb 06 2010