OFFSET
0,2
COMMENTS
Terms at positions 2^k is found in A107958.
EXAMPLE
PROG
(PARI) {a(n)=local(A=[1, 2]); for(i=1, #binary(n), B=vector(#A, k, polcoeff(Ser(A)/(1-x), k-1)+A[2^#binary(#A-1)]); A=concat(A, B); ); sum(k=1, n, A[k])}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, May 29 2005
STATUS
approved