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 A067220 #12 Oct 14 2024 10:55:31 %S A067220 1,13,169,112489,10309971465,121778484808846083, %T A067220 193842679171307621077398205 %N A067220 Number of n X n 0..12 matrices with all row and column sums equal. %Y A067220 Column k=12 of A202784. %K A067220 nonn,more %O A067220 0,2 %A A067220 _R. H. Hardin_, Feb 20 2002 %E A067220 a(5)-a(6) from _Sean A. Irvine_, Dec 11 2023 %E A067220 a(0)=1 prepended by _Andrew Howroyd_, Oct 14 2024