A344303 Number of cyclic subgroups of the group (C_n)^7, where C_n is the cyclic group of order n.

1, 128, 1094, 8256, 19532, 140032, 137258, 528448, 797891, 2500096, 1948718, 9032064, 5229044, 17569024, 21368008, 33820736, 25646168, 102130048, 49659542, 161256192, 150160252, 249435904, 154764794, 578122112, 305191407, 669317632, 581662904, 1133202048

Offset

1,2

Comments

Inverse Moebius transform of A160897.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

László Tóth, On the number of cyclic subgroups of a finite abelian group, arXiv: 1203.6201 [math.GR], 2012.

Formula

a(n) = Sum_{x_1|n, x_2|n, ..., x_7|n} phi(x_1)*phi(x_2)* ... *phi(x_7)/phi(lcm(x_1, x_2, ..., x_7)).

If p is prime, a(p) = 1 + (p^7 - 1)/(p - 1).

From Amiram Eldar, Nov 15 2022: (Start)

Multiplicative with a(p^e) = 1 + ((p^7 - 1)/(p - 1))*((p^(6*e) - 1)/(p^6 - 1)).

Sum_{k=1..n} a(k) ~ c * n^7, where c = (zeta(7)/7) * Product_{p prime} ((1-1/p^6)/(p^2*(1-1/p))) = 0.2784611791... . (End)

Mathematica

f[p_, e_] := 1 + ((p^7 - 1)/(p - 1))*((p^(6*e) - 1)/(p^6 - 1)); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 30] (* Amiram Eldar, Nov 15 2022 *)

Prog

(PARI) a160897(n) = sumdiv(n, d, moebius(n/d)*d^7)/eulerphi(n);
a(n) = sumdiv(n, d, a160897(d));

Crossrefs

Cf. A000010, A013665, A060648, A064969, A280184, A344219, A344302, A344304, A344305, A344306.

Sequence in context: A130813 A206278 A100628 * A221599 A134630 A133061

Adjacent sequences: A344300 A344301 A344302 * A344304 A344305 A344306

Keyword

nonn,mult

Author

Seiichi Manyama, May 14 2021

Status

approved