OFFSET
0,3
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..250
FORMULA
G.f. A(x) satisfies: A(x) = Sum_{j>=0} x^j * Sum_{k=0..j} k!*Stirling2(j,k)*A(x)^k.
a(n) ~ exp(1/2) * n! / (2 * (log(2))^(n+1)). - Vaclav Kotesovec, Apr 10 2019
EXAMPLE
G.f.: A(x) = 1 + x + 4*x^2 + 22*x^3 + 150*x^4 + 1198*x^5 + 10900*x^6 + 111392*x^7 + 1268816*x^8 + 16029676*x^9 + 223672208*x^10 + ...
MATHEMATICA
terms = 22; A[_] = 1; Do[A[x_] = Sum[j! x^j A[x]^j/Product[(1 - k x), {k, 1, j}], {j, 0, i}] + O[x]^i, {i, 1, terms}]; CoefficientList[A[x], x]
terms = 22; A[_] = 1; Do[A[x_] = Sum[x^j Sum[k! StirlingS2[j, k] A[x]^k, {k, 0, j}], {j, 0, i}] + O[x]^i, {i, 1, terms}]; CoefficientList[A[x], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 08 2019
STATUS
approved