A318677 Sum of divisors of n that have an odd number of prime factors (counted with multiplicity).

0, 2, 3, 2, 5, 5, 7, 10, 3, 7, 11, 17, 13, 9, 8, 10, 17, 23, 19, 27, 10, 13, 23, 25, 5, 15, 30, 37, 29, 40, 31, 42, 14, 19, 12, 35, 37, 21, 16, 35, 41, 54, 43, 57, 53, 25, 47, 73, 7, 57, 20, 67, 53, 50, 16, 45, 22, 31, 59, 72, 61, 33, 73, 42, 18, 82, 67, 87, 26, 84, 71, 115, 73, 39, 83, 97, 18, 96, 79, 115, 30, 43, 83, 94, 22, 45, 32

Offset

1,2

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} [A008836(d) < 0]*d.

a(n) = A000203(n) - A318677(n).

For all n >= 1, a(n) >= A318675(n).

Mathematica

Array[DivisorSum[#, # &, OddQ@ PrimeOmega@ # &] &, 87] (* Michael De Vlieger, Sep 04 2018 *)

Prog

(PARI) A318677(n) = sumdiv(n, d, (bigomega(d)%2)*d);

Crossrefs

Cf. A000203, A008836, A318675, A318676.

Sequence in context: A068319 A133775 A099043 * A239327 A021047 A249492

Adjacent sequences: A318674 A318675 A318676 * A318678 A318679 A318680

Keyword

nonn

Author

Antti Karttunen, Sep 04 2018

Status

approved