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A284151
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Sum_{d|n, d=1 or 6 mod 7} d.
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3
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1, 1, 1, 1, 1, 7, 1, 9, 1, 1, 1, 7, 14, 1, 16, 9, 1, 7, 1, 21, 1, 23, 1, 15, 1, 14, 28, 1, 30, 22, 1, 9, 1, 35, 1, 43, 1, 1, 14, 29, 42, 7, 44, 23, 16, 1, 1, 63, 1, 51, 1, 14, 1, 34, 56, 9, 58, 30, 1, 42, 1, 63, 1, 73, 14, 29, 1, 35, 70, 1, 72, 51, 1, 1, 16, 77, 1
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OFFSET
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1,6
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LINKS
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FORMULA
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MATHEMATICA
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Table[Sum[If[Mod[d, 7] == 1 || Mod[d, 7]==6, d, 0], {d, Divisors[n]}], {n, 80}] (* Indranil Ghosh, Mar 21 2017 *)
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PROG
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(PARI) for(n=1, 80, print1(sumdiv(n, d, if(d%7==1 || d%7==6, d, 0)), ", ")) \\ Indranil Ghosh, Mar 21 2017
(Python)
from sympy import divisors
def a(n): return sum([d for d in divisors(n) if d%7==1 or d%7 == 6]) # Indranil Ghosh, Mar 21 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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