OFFSET
0,2
LINKS
Eric Weisstein's World of Mathematics, Lambert W-Function.
FORMULA
E.g.f.: A(x) = exp( x - 2/3 * LambertW(-3*x/2 * exp(3*x/2)) ).
If e.g.f. satisfies A(x) = exp( r*x*A(x)^(t/r) * (1 + A(x)^(u/r)) ), then a(n) = r * Sum_{k=0..n} (t*n+u*k+r)^(n-1) * binomial(n,k).
G.f.: Sum_{k>=0} (3*k/2+1)^(k-1) * x^k/(1 - (3*k/2+1)*x)^(k+1).
a(n) ~ sqrt(1 + LambertW(exp(-1))) * 3^(n-1) * n^(n-1) / (2^(n-1) * exp(n) * LambertW(exp(-1))^(n + 2/3)). - Vaclav Kotesovec, Apr 24 2024
PROG
(PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(x-2/3*lambertw(-3*x/2*exp(3*x/2)))))
(PARI) a(n, r=1, t=0, u=3/2) = r*sum(k=0, n, (t*n+u*k+r)^(n-1)*binomial(n, k));
(PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (3*k/2+1)^(k-1)*x^k/(1-(3*k/2+1)*x)^(k+1)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 24 2024
STATUS
approved