OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..419
FORMULA
a(n) = Sum_{k=0..n} Stirling1(n, k)*k!*2^k.
a(n) ~ n! * exp(1/2) / (2 * (exp(1/2)-1)^(n+1)). - Vaclav Kotesovec, May 03 2015
a(0) = 1; a(n) = 2 * Sum_{k=1..n} (-1)^(k-1) * (k-1)! * binomial(n,k) * a(n-k). - Seiichi Manyama, May 22 2022
MATHEMATICA
CoefficientList[Series[1/(1-2*Log[1+x]), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, May 03 2015 *)
PROG
(PARI) a(n) = sum(k=0, n, k!*2^k*stirling(n, k, 1)); \\ Seiichi Manyama, Feb 03 2022
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1-2*log(1+x)))) \\ Seiichi Manyama, Feb 03 2022
(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=2*sum(j=1, i, (-1)^(j-1)*(j-1)!*binomial(i, j)*v[i-j+1])); v; \\ Seiichi Manyama, May 22 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Nov 12 2003
STATUS
approved