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

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

(PARI) A318679(n) = sumdiv(n, d, d=sigma(d)-(2*d); (d>0)*d);

Crossrefs

Cf. A033880, A187795, A296075, A318441, A318442, A318678.

Sequence in context: A075444 A280492 A089371 * A133886 A061859 A348250

Adjacent sequences: A318676 A318677 A318678 * A318680 A318681 A318682

Keyword

nonn

Author

Antti Karttunen, Sep 04 2018

Status

approved