login
A318679
Sum of abundancies of abundant divisors of n.
3
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
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
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 04 2018
STATUS
approved