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 A133720 #7 Sep 13 2015 21:05:59 %S A133720 1,34,561,5087,30569,138103,507360,1594272,4433484,11176033,25989535, %T A133720 56493801,115960208,226569266,424098592,764503872,1332959307, %U A133720 2256042444,3717882133,5981238571,9414651939,14526981953,22010865680,32796846160 %N A133720 Column 5 of array in A133713. %p A133720 A133720 := proc(l) %p A133720 A133713(l,5) ; %p A133720 end proc: %p A133720 seq(A133720(l),l=2..30) ; # _R. J. Mathar_, Nov 23 2011 %K A133720 nonn %O A133720 2,2 %A A133720 _N. J. A. Sloane_, Dec 30 2007