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 A172743 #10 Apr 18 2020 22:23:29 %S A172743 1,7,55,415,3391,28681,248137,2186815,19546975,176703337,1612210777, %T A172743 14823083089,137176167025,1276548044695,11936862061495, %U A172743 112092031526335,1056512066133055,9991003788000025,94760438267696425,901154863603211665 %N A172743 Number of n X 3 0..3 arrays with row sums 3 and column sums n. %H A172743 R. H. Hardin, <a href="/A172743/b172743.txt">Table of n, a(n) for n=1..99</a> %Y A172743 Column k=3 of A333901. %K A172743 nonn %O A172743 1,2 %A A172743 _R. H. Hardin_, Feb 06 2010