A355929 Difference between the squarefree part of the sum of divisors of n and the squarefree part of n.

0, 1, -2, 6, 1, -3, -5, 13, 12, -8, -8, 4, 1, -8, -9, 30, -15, 37, -14, 37, -19, -21, -17, 9, 30, 16, 7, 7, 1, -28, -29, 5, -30, -28, -32, 90, 1, -23, -25, 0, 1, -36, -32, 10, 73, -44, -44, 28, 56, 91, -49, -11, -47, 24, -53, 16, -52, -48, -44, 27, 1, -56, 19, 126, -44, -65, -50, -3, -63, -69, -69, 193, 1, 40, 28, 16

Offset: 1

Author

Antti Karttunen, Jul 24 2022

Keywords

• sign

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A007913, A069070 (positions of 0's), A355928.

Programs

PARI

A355929(n) = (core(sigma(n))-core(n));

Formula

a(n) = A355928(n) - A007913(n) = A007913(A000203(n)) - A007913(n).