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 A132290 #2 Mar 30 2012 18:37:04
%S A132290 1,2,6,25,129,771,5172,38280,308987,2695586,25231269,251869681,
%T A132290 2667876382,29856632341,351717286357,4347357161694,56222019376378,
%U A132290 758836553993985,10665452531786380,155785594704483911
%N A132290 Main diagonal of triangle A132289: a(n) = A132289(n,n) for n>=0.
%C A132290 Equals the binomial transform of A125276.
%F A132290 G.f. A(x) satisfies: A( x*(1-x)/(1+x-x^2) )/(1+x-x^2) = 1 + x*A(x).
%o A132290 (PARI) {a(n)=local(A=[1]);if(n==0,1,for(i=1,n, A=Vec(Ser(concat(concat(A[ #A],A),A[ #A]))/(1-x)));A[n+1])}
%Y A132290 Cf. A132289, A125276.
%K A132290 nonn
%O A132290 0,2
%A A132290 _Paul D. Hanna_, Aug 18 2007