%I #3 Mar 30 2012 18:36:46
%S 1,1,2,5,16,68,399,3348,41417,775234,22445788,1024347395,74876701760,
%T 8888457145166,1734062627778860
%N Terms at positions 2^n of A107946 for n>=0.
%F a(n) = A107946(2^n).
%o (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 Cf. A107946, A107947.
%K nonn
%O 0,3
%A _Paul D. Hanna_, May 28 2005