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 A107948 #3 Mar 30 2012 18:36:46
%S A107948 1,1,2,5,16,68,399,3348,41417,775234,22445788,1024347395,74876701760,
%T A107948 8888457145166,1734062627778860
%N A107948 Terms at positions 2^n of A107946 for n>=0.
%F A107948 a(n) = A107946(2^n).
%o A107948 (PARI) {a(n)=local(A=[1,1],B=[1]);for(i=1,n-1, B=concat(B,vector(#B,k,polcoeff(Ser(A)/(1-x),#B+k-1))); A=concat(A,B););A[2^(n-1)]}
%Y A107948 Cf. A107946, A107947.
%K A107948 nonn
%O A107948 0,3
%A A107948 _Paul D. Hanna_, May 28 2005