A377584 E.g.f.: exp(Sum_{k>=1} A326305(k) * x^k/k).

1, 1, 1, 5, 23, 167, 907, 8647, 84625, 840401, 8917289, 122748749, 1753750759, 26047588855, 401961006787, 6422475692063, 124830139084193, 2445151343123873, 48495757104590545, 1038849234759346069, 23966120552360409271, 545230613480963786951, 13288745250263697838331

Offset: 0

Author

Vaclav Kotesovec, Nov 02 2024

Keywords

• nonn

Crossrefs

Cf. A326305.

Programs

Mathematica

nmax = 25; CoefficientList[Series[Exp[Sum[If[OddQ[k], EulerPhi[k], EulerPhi[k] - EulerPhi[k/2]]*x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x] * Range[0, nmax]!

Formula

a(n) ~ sqrt(3) * exp(3*sqrt(2*n)/Pi - n) * n^(n - 1/4) / (2^(3/4) * sqrt(Pi)).