A325815 a(n) = A324213(n) - A034444(n).

1, 2, 1, 6, 2, -2, 2, 14, 10, 5, 4, 10, 4, 8, 4, 30, 8, 22, 6, 17, 10, 14, 10, 16, 28, 12, 16, -2, 12, 16, 8, 62, 12, 20, 18, 84, 12, 26, 22, 32, 16, 24, 12, 38, 22, 24, 22, 50, 54, 76, 16, 28, 24, 36, 32, 56, 34, 38, 28, 48, 16, 38, 44, 126, 38, 40, 20, 46, 24, 64, 24, 118, 24, 50, 54, 42, 44, 48, 24, 82, 118, 56, 40, 88, 50, 48, 36, 86, 40

Offset: 1

Author

Antti Karttunen, May 29 2019

Keywords

• sign

Links

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

Crossrefs

Cf. A000396, A034444, A324213, A325816.

Programs

PARI

A034444(n) = (2^omega(n));
A324213(n) = { my(s=sigma(n)); sum(i=0, s, (1==gcd(n-i, n-(s-i)))); };
A325815(n) = (A324213(n)-A034444(n));

Formula

a(n) = A324213(n) - A034444(n).

a(A000396(n)) < 0 for all n.