A318679 - OEIS

A318679

Sum of abundancies of abundant divisors of n.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 3, 0, 2, 0, 0, 0, 16, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 26, 0, 0, 0, 12, 0, 12, 0, 0, 0, 0, 0, 44, 0, 0, 0, 0, 0, 15, 0, 8, 0, 0, 0, 66, 0, 0, 0, 0, 0, 12, 0, 0, 0, 4, 0, 89, 0, 0, 0, 0, 0, 12, 0, 38, 0, 0, 0, 72, 0, 0, 0, 4, 0, 69, 0, 0, 0, 0, 0, 104, 0, 0, 0, 19, 0, 12, 0, 2, 0

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OFFSET

1,12

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for sequences related to sigma(n)

FORMULA

a(n) = Sum_{d|n} [A033880(d) > 0]*A033880(d).

a(n) = A318678(n) - A296075(n).

MATHEMATICA

f[n_] := DivisorSigma[1, n] - 2 n; Array[DivisorSum[#, f, f@ # >= 0 &] &, 105] (* Michael De Vlieger, Sep 04 2018 *)

PROG