A372676 a(n) = phi(11 * n)/10.

1, 1, 2, 2, 4, 2, 6, 4, 6, 4, 11, 4, 12, 6, 8, 8, 16, 6, 18, 8, 12, 11, 22, 8, 20, 12, 18, 12, 28, 8, 30, 16, 22, 16, 24, 12, 36, 18, 24, 16, 40, 12, 42, 22, 24, 22, 46, 16, 42, 20, 32, 24, 52, 18, 44, 24, 36, 28, 58, 16, 60, 30, 36, 32, 48, 22, 66, 32, 44, 24, 70, 24, 72, 36, 40, 36

Offset

1,3

Links

Table of n, a(n) for n=1..76.

Formula

G.f.: -Sum_{k>=1} mu(11 * k) * x^k / (1 - x^k)^2, where mu() is the Moebius function (A008683).

Multiplicative with a(11^e) = 11^e, and a(p^e) = (p-1)*p^(e-1) if p != 11.

Sum_{k=1..n} a(k) ~ (121/(40*Pi^2)) * n^2. - Amiram Eldar, May 10 2024

Mathematica

a[n_] := EulerPhi[11 * n]/10; Array[a, 100] (* Amiram Eldar, May 10 2024 *)

Prog

(PARI) a(n) = eulerphi(11*n)/10;
(PARI) my(N=80, x='x+O('x^N)); Vec(-sum(k=1, N, moebius(11*k)*x^k/(1-x^k)^2))

Crossrefs

Column k=11 of A372673.

Cf. A008683.

Sequence in context: A372677 A003978 A122645 * A122646 A028496 A063428

Adjacent sequences: A372673 A372674 A372675 * A372677 A372678 A372679

Keyword

nonn,mult,easy

Author

Seiichi Manyama, May 10 2024

Status

approved