OFFSET
0,1
COMMENTS
FORMULA
G.f.: A(x) = 1+x - x^2*(1+x)/(1+x^2) + Sum_{k>=1} x^(3*2^(k-1))/Product_{j=0..k} (1+x^(2^j)).
PROG
(PARI) {a(n)=polcoeff(A=1+x-x^2*(1+x)/(1+x^2)+ sum(k=1, #binary(n), x^(3*2^(k-1))/prod(j=0, k, 1+x^(2^j)+x*O(x^n))), n)}
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Jul 09 2005
STATUS
approved