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A377584
E.g.f.: exp(Sum_{k>=1} A326305(k) * x^k/k).
0
1, 1, 1, 5, 23, 167, 907, 8647, 84625, 840401, 8917289, 122748749, 1753750759, 26047588855, 401961006787, 6422475692063, 124830139084193, 2445151343123873, 48495757104590545, 1038849234759346069, 23966120552360409271, 545230613480963786951, 13288745250263697838331
OFFSET
0,4
FORMULA
a(n) ~ sqrt(3) * exp(3*sqrt(2*n)/Pi - n) * n^(n - 1/4) / (2^(3/4) * sqrt(Pi)).
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]!
CROSSREFS
Cf. A326305.
Sequence in context: A054749 A107204 A178383 * A167576 A306180 A308443
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Nov 02 2024
STATUS
approved