A074627 Numbers n such that sigma(n) is divisible by 6.

5, 6, 10, 11, 14, 15, 17, 20, 22, 23, 24, 26, 29, 30, 33, 34, 35, 38, 40, 41, 42, 44, 45, 46, 47, 51, 53, 54, 55, 56, 58, 59, 60, 62, 65, 66, 68, 69, 70, 71, 74, 77, 78, 80, 82, 83, 85, 86, 87, 88, 89, 90, 92, 94, 95, 96, 99, 101, 102, 104, 105, 106, 107, 110, 113, 114, 115

Offset: 1

Author

Labos Elemer, Aug 26 2002

Keywords

• easy
• nonn

Comments

n=10: sigma(10) = 1+2+5+10 = 18 = 3*6.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A072862, A074384, A074628, A067051, A074630.

Programs

Mathematica

Select[Range@ 120, Divisible[DivisorSigma[1, #], 6] &] (* Michael De Vlieger, Feb 25 2017 *)

PARI

isok(n) = !(sigma(n) % 6); \\ Michel Marcus, Dec 17 2013

Formula

A000203(n) modulo 6 = 0.

{n: A084301(n) = 0 }. - R. J. Mathar, May 19 2020

A087943 INTERSECT A028983. - R. J. Mathar, May 19 2020