A297170 a(n) = gcd(phi(n), sigma(n)-n).

1, 1, 1, 1, 1, 2, 1, 1, 2, 4, 1, 4, 1, 2, 1, 1, 1, 3, 1, 2, 1, 2, 1, 4, 2, 4, 1, 4, 1, 2, 1, 1, 5, 4, 1, 1, 1, 2, 1, 2, 1, 6, 1, 20, 3, 2, 1, 4, 2, 1, 1, 2, 1, 6, 1, 8, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 4, 1, 4, 1, 6, 1, 2, 2, 4, 1, 4, 1, 2, 1, 4, 1, 24, 3, 4, 5, 2, 1, 4, 1, 1, 3, 1, 1, 2, 1, 2, 3

Offset: 1

Author

Antti Karttunen, Mar 03 2018

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A000010, A000203, A001065, A009223.

Programs

PARI

A297170(n) = gcd(eulerphi(n),sigma(n)-n);

Formula

a(n) = gcd(A000010(n), A001065(n)).