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A284587 Sum of the divisors of n that are not divisible by 13. 4
1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 12, 28, 1, 24, 24, 31, 18, 39, 20, 42, 32, 36, 24, 60, 31, 3, 40, 56, 30, 72, 32, 63, 48, 54, 48, 91, 38, 60, 4, 90, 42, 96, 44, 84, 78, 72, 48, 124, 57, 93, 72, 7, 54, 120, 72, 120, 80, 90, 60, 168, 62, 96, 104, 127, 6, 144, 68 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

G.f.: Sum_{k>=1} k*x^k/(1 - x^k) - 13*k*x^(13*k)/(1 - x^(13*k)). - Ilya Gutkovskiy, Mar 30 2017

MATHEMATICA

Table[Sum[Boole[Mod[d, 13]>0] d , {d, Divisors[n]}], {n, 100}] (* Indranil Ghosh, Mar 29 2017 *)

PROG

(PARI) a(n)=sumdiv(n, d, ((d%13)>0)*d); \\ Andrew Howroyd, Jul 20 2018

CROSSREFS

Cf. A133099.

Sum of the divisors of n that are not divisible by k: A046913 (k=3), A046897 (k=4), A116073 (k=5), A284326 (k=6), A113957 (k=7), A284341 (k=8), A116607 (k=9), A284344 (k=10), this sequence (k=13), A227131 (k=25).

Sequence in context: A069192 A076887 A140782 * A097011 A074847 A325317

Adjacent sequences:  A284584 A284585 A284586 * A284588 A284589 A284590

KEYWORD

nonn,mult

AUTHOR

Seiichi Manyama, Mar 29 2017

EXTENSIONS

Keyword:mult added by Andrew Howroyd, Jul 20 2018

STATUS

approved

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Last modified November 19 03:37 EST 2019. Contains 329310 sequences. (Running on oeis4.)