A063514 a(n) = sigma(n) mod phi(n).

0, 0, 0, 1, 2, 0, 2, 3, 1, 2, 2, 0, 2, 0, 0, 7, 2, 3, 2, 2, 8, 6, 2, 4, 11, 6, 4, 8, 2, 0, 2, 15, 8, 6, 0, 7, 2, 6, 8, 10, 2, 0, 2, 4, 6, 6, 2, 12, 15, 13, 8, 2, 2, 12, 32, 0, 8, 6, 2, 8, 2, 6, 32, 31, 36, 4, 2, 30, 8, 0, 2, 3, 2, 6, 4, 32, 36, 0, 2, 26, 13, 6, 2

Offset

1,5

Comments

If a(n) = 0, then n is a balanced number (A020492).

Links

Harry J. Smith, Table of n, a(n) for n = 1..2000

Formula

a(p^2) = 2*p+1, for prime p >= 5. - Michel Marcus, Apr 07 2020

Mathematica

a[n_] := Mod[DivisorSigma[1, n], EulerPhi[n]]; Array[a, 100] (* Amiram Eldar, Dec 25 2024 *)

Prog

(PARI) a(n) = { sigma(n)%eulerphi(n) } \\ Harry J. Smith, Aug 24 2009
(Magma) [SumOfDivisors(n) mod EulerPhi(n): n in [1..85]]; // Bruno Berselli, Jan 31 2013

Crossrefs

Cf. A000010, A000203, A020492, A023897.

Sequence in context: A073450 A284592 A071447 * A082490 A328591 A210635

Adjacent sequences: A063511 A063512 A063513 * A063515 A063516 A063517

Keyword

nonn,easy

Author

Labos Elemer, Jul 31 2001

Status

approved