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A187795
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Sum of the abundant divisors of n.
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16
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 18, 0, 20, 0, 0, 0, 36, 0, 0, 0, 0, 0, 30, 0, 0, 0, 0, 0, 66, 0, 0, 0, 60, 0, 42, 0, 0, 0, 0, 0, 84, 0, 0, 0, 0, 0, 72, 0, 56, 0, 0, 0, 122, 0, 0, 0, 0, 0, 66, 0, 0, 0, 70, 0, 162, 0, 0, 0, 0, 0, 78, 0, 140, 0, 0, 0, 138, 0, 0, 0, 88, 0, 138, 0, 0, 0, 0, 0, 180
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OFFSET
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1,12
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COMMENTS
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Sum of divisors d of n with sigma(d) > 2*d.
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LINKS
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FORMULA
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(End)
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EXAMPLE
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a(12) = 12 because the divisors of 12 are 1, 2, 3, 4, 6, 12, but of those only 12 is abundant.
a(13) = 0 because the divisors of 13 are 1 and 13, neither of which is abundant.
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MAPLE
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local a, d;
a :=0 ;
for d in numtheory[divisors](n) do
if numtheory[sigma](d) > 2* d then
a := a+d ;
end if;
end do:
return a;
end proc:
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MATHEMATICA
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Table[Total@ Select[Divisors@ n, DivisorSigma[1, #] > 2 # &], {n, 96}] (* Michael De Vlieger, Jul 16 2016 *)
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PROG
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(Python)
from sympy import divisors, divisor_sigma
def A187795(n): return sum(d for d in divisors(n, generator=True) if divisor_sigma(d) > 2*d) # Chai Wah Wu, Sep 22 2021
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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