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 A121414 #3 Mar 30 2012 18:36:58
%S A121414 1,1,5,45,581,9730,199692,4843125,135345925,4278317373,150818840250,
%T A121414 5863215069621,249105031449435,11480173020040450,570303168053225908,
%U A121414 30375972794764190385,1726700205634807475115,104332294453480284687895
%N A121414 Column 2 of triangle A121412, in which row n of T=A121412 equals row (n-1) of T^(n+1) with an appended '1'.
%C A121414 Also equals column 4 of triangle A101479.
%o A121414 (PARI) {a(n)=local(A=Mat(1), B); for(m=1, n+3, B=matrix(m, m); for(i=1, m, for(j=1, i, if(j==i, B[i, j]=1, B[i, j]=(A^i)[i-1, j]); )); A=B); return((A^1)[n+3, 3])}
%Y A121414 Cf. A121412 (triangle); other columns: A101483, A121413, A121415; A101479 (triangle).
%K A121414 nonn
%O A121414 0,3
%A A121414 _Paul D. Hanna_, Aug 22 2006