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%I #4 Mar 30 2012 18:36:46
%S 1,3,11,52,331,2949,38069,733817,21670554,1001901607,73852354365,
%T 8813580443406,1725174170633694
%N a(n) = term at position 2^n in A107957.
%C Also terms at positions 2^(n+1) - 1 of A107947, where A107947 equals the first differences of A107957.
%F a(n) = A107957(2^n). a(n) = A107947(2^(n+1) - 1).
%o (PARI) {a(n)=local(A=[1,2]);for(i=1,n, B=vector(#A,k,polcoeff(Ser(A)/(1-x),k-1)+A[2^#binary(#A-1)]); A=concat(A,B););sum(k=1,2^n,A[k])}
%Y Cf. A107946, A107947, A107948, A107957.
%K nonn
%O 0,2
%A _Paul D. Hanna_, May 29 2005