OFFSET
0,4
EXAMPLE
G.f.: A(x) = 1 + x + x^2 + 6*x^3 + 12*x^4 + 19*x^5 + 48*x^6 +...
log(A(x)) = x + x^2/2 + 4^2*x^3/3 + 5^2*x^4/4 + 6^2*x^5/5 + 10^2*x^6/6 +...
where the coefficients are the squares of the coefficients in L(x):
L(x) = log(1 + x + x^3 + x^7 + x^15 +...+ x^(2^n-1) +...);
L(x) = x - x^2/2 + 4*x^3/3 - 5*x^4/4 + 6*x^5/5 - 10*x^6/6 + 22*x^7/7 -+...
PROG
(PARI) {a(n)=local(L=Vec(log(sum(m=0, #binary(n), x^(2^m-1))+x*O(x^n)))); polcoeff(exp(sum(k=1, n, L[k]^2*k*x^k)+x*O(x^n)), n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 02 2009
STATUS
approved