A074628 Numbers k such that sigma(k) == 2 mod 6.

7, 13, 19, 21, 28, 31, 37, 39, 43, 52, 57, 61, 63, 67, 73, 76, 79, 84, 93, 97, 103, 109, 111, 112, 117, 124, 127, 129, 139, 148, 151, 156, 157, 163, 171, 172, 175, 181, 183, 189, 193, 199, 201, 208, 211, 219, 223, 228, 229, 237, 241, 244, 252

Offset

1,1

Links

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

Formula

A000203(n) mod 6 = 2.

{n: A084301(n) = 2}. - R. J. Mathar, May 19 2020

Example

For k=39: sigma(39) = 1+3+13+39 = 56 = 6*9 + 2.

Mathematica

Select[Range[300], Mod[DivisorSigma[1, #], 6]==2&] (* Harvey P. Dale, Nov 14 2014 *)

Prog

(PARI) isok(n) = ((sigma(n) % 6) == 2); \\ Michel Marcus, Dec 19 2013

Crossrefs

Cf. A000203, A072862, A074384, A074627, A074628, A074629, A074630.

Sequence in context: A160007 A024613 A024606 * A232436 A274437 A031194

Adjacent sequences: A074625 A074626 A074627 * A074629 A074630 A074631

Keyword

easy,nonn

Author

Labos Elemer, Aug 26 2002

Status

approved