A325313 a(n) = A048250(n) - n, where A048250(n) is the sum of squarefree divisors of n.

0, 1, 1, -1, 1, 6, 1, -5, -5, 8, 1, 0, 1, 10, 9, -13, 1, -6, 1, -2, 11, 14, 1, -12, -19, 16, -23, -4, 1, 42, 1, -29, 15, 20, 13, -24, 1, 22, 17, -22, 1, 54, 1, -8, -21, 26, 1, -36, -41, -32, 21, -10, 1, -42, 17, -32, 23, 32, 1, 12, 1, 34, -31, -61, 19, 78, 1, -14, 27, 74, 1, -60, 1, 40, -51, -16, 19, 90, 1, -62, -77, 44, 1, 12, 23, 46

Offset: 1

Author

Antti Karttunen, Apr 21 2019

Keywords

• sign

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384
• Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

Crossrefs

Cf. A033879, A048250, A126795, A228058, A325314, A325315, A325319, A325320.

Programs

Mathematica

Array[DivisorSum[#, # &, SquareFreeQ] - # &, 86] (* Michael De Vlieger, Apr 21 2019 *)

PARI

A048250(n) = factorback(apply(p -> p+1,factor(n)[,1]));
A325313(n) = (A048250(n) - n);

Formula

a(n) = A048250(n) - n.

a(n) = A325314(n) - A033879(n).

a(A228058(n)) = -A325319(n).