A346581 a(n) = (1/(7*n)) * Sum_{d|n} mu(n/d) * binomial(7*d,d).

1, 6, 63, 728, 9275, 124866, 1753073, 25365600, 375677595, 5667202850, 86775157139, 1345153422600, 21069043965983, 332927798516614, 5301031234076325, 84967018610221440, 1369846562874360886, 22199151535757655354, 361411377745122110421, 5908312923789590118600

Offset: 1

Author

Ilya Gutkovskiy, Jul 24 2021

Keywords

• nonn

Comments

Inverse Euler transform of A002296.

Moebius transform of A261500.

Crossrefs

Cf. A002296, A004368, A008683, A022553, A261500, A346577, A346578, A346579, A346580, A346582.

Programs

Mathematica

Table[(1/(7 n)) Sum[MoebiusMu[n/d] Binomial[7 d, d], {d, Divisors[n]}], {n, 20}]

PARI

a(n) = sumdiv(n, d, moebius(n/d)*binomial(7*d,d))/(7*n); \\ Michel Marcus, Jul 24 2021