A097012 a(n) = sigma(n) mod 210.

1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 12, 28, 14, 24, 24, 31, 18, 39, 20, 42, 32, 36, 24, 60, 31, 42, 40, 56, 30, 72, 32, 63, 48, 54, 48, 91, 38, 60, 56, 90, 42, 96, 44, 84, 78, 72, 48, 124, 57, 93, 72, 98, 54, 120, 72, 120, 80, 90, 60, 168, 62, 96, 104, 127, 84, 144, 68, 126, 96

Offset

1,2

Comments

Agrees with A000203(n) for n <= 89; sigma(90) = 234. - Omar E. Pol, Feb 02 2013

This sequence is not multiplicative. For example, at a(84) = 14 which is not a(3)*a(4)*a(7) = 224. - Andrew Howroyd, Aug 23 2018

Links

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

Formula

a(n) = A000203(n) mod 210.

Mathematica

Array[Mod[DivisorSigma[1, #], 210] &, 69] (* Michael De Vlieger, Jul 24 2017 *)

Prog

(PARI) a(n) = sigma(n) % 210; \\ Michel Marcus, Dec 19 2013
(Magma) [SumOfDivisors(n) mod 210: n in [1..70]]; // Vincenzo Librandi, Jul 25 2017

Crossrefs

Cf. A000203, A084301, A084303, A097011, A097013, A097014, A097015.

Sequence in context: A365209 A097863 A287926 * A143348 A000203 A324545

Adjacent sequences: A097009 A097010 A097011 * A097013 A097014 A097015

Keyword

nonn

Author

Labos Elemer, Aug 19 2004

Status

approved