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A097012 a(n) = sigma(n) mod 210. 5
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 (list; graph; refs; listen; history; text; internal format)
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: A227131 A097863 A287926 * A143348 A000203 A324545

Adjacent sequences:  A097009 A097010 A097011 * A097013 A097014 A097015

KEYWORD

nonn

AUTHOR

Labos Elemer, Aug 19 2004

STATUS

approved

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Last modified January 28 06:00 EST 2021. Contains 340490 sequences. (Running on oeis4.)