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A284150
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Sum_{d|n, d==1 or 4 mod 5} d.
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6
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1, 1, 1, 5, 1, 7, 1, 5, 10, 1, 12, 11, 1, 15, 1, 21, 1, 16, 20, 5, 22, 12, 1, 35, 1, 27, 10, 19, 30, 7, 32, 21, 12, 35, 1, 56, 1, 20, 40, 5, 42, 42, 1, 60, 10, 47, 1, 51, 50, 1, 52, 31, 1, 70, 12, 75, 20, 30, 60, 11, 62, 32, 31, 85, 1, 84, 1, 39, 70, 15, 72, 80, 1
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OFFSET
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1,4
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LINKS
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FORMULA
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MAPLE
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a := 0 ;
for d in numtheory[divisors](n) do
if modp(d, 5) in {1, 4} then
a := a+d ;
end if;
end do:
a ;
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MATHEMATICA
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Table[Sum[If[Mod[d, 5] == 1 || Mod[d, 5]==4, 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%5==1 || d%5 ==4, 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%5==1 or d%5 == 4]) # 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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