OFFSET
0,3
COMMENTS
Compare to g.f. of A157675: G(x) = exp( Sum_{n>=1} G(2^n*x)^n*x^n/n ).
FORMULA
Limit a(n) / 2^(n*(n-1)/2) = 2.494435637496531683539561928813688982084486211124...
EXAMPLE
G.f.: A(x) = 1 + x + 3*x^2 + 15*x^3 + 139*x^4 + 2387*x^5 +...
log(A(x)) = A(2x) + A(4x^2)*x^2/2 + A(8x^3)*x^3/3 + A(16x^4)*x^4/4 +...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=exp(sum(m=1, n, subst(A, x, 2^m*x^m+x*O(x^n))*x^m/m))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 15 2010
STATUS
approved