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A293897 Sum of proper divisors of the form 3k+1. 5
0, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 5, 1, 8, 1, 5, 1, 1, 1, 15, 8, 1, 1, 5, 1, 14, 1, 12, 1, 11, 1, 21, 1, 1, 8, 5, 1, 20, 14, 15, 1, 8, 1, 27, 1, 1, 1, 21, 8, 36, 1, 18, 1, 1, 1, 40, 20, 1, 1, 15, 1, 32, 8, 21, 14, 23, 1, 39, 1, 18, 1, 5, 1, 38, 26, 24, 8, 14, 1, 71, 1, 1, 1, 40, 1, 44, 1, 27, 1, 11, 21, 51, 32, 1, 20, 21, 1, 57, 1, 40, 1, 35, 1, 70, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences related to sums of divisors

FORMULA

a(n) = A078181(n) - ([n == 1 (mod 3)]*n).

MATHEMATICA

Table[DivisorSum[n, # &, And[Mod[#, 3] == 1, # != n] &], {n, 105}] (* Michael De Vlieger, Nov 08 2017 *)

PROG

(PARI) A293897(n) = sumdiv(n, d, (d<n)*(1==(d%3))*d);

CROSSREFS

Cf. A078181, A293901, A293895, A293898.

Sequence in context: A089608 A250131 A100615 * A222119 A102280 A035316

Adjacent sequences:  A293894 A293895 A293896 * A293898 A293899 A293900

KEYWORD

nonn

AUTHOR

Antti Karttunen, Nov 06 2017

STATUS

approved

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Last modified May 22 06:32 EDT 2019. Contains 323478 sequences. (Running on oeis4.)