A325636 a(n) = gcd(2n, sigma(n)).

1, 1, 2, 1, 2, 12, 2, 1, 1, 2, 2, 4, 2, 4, 6, 1, 2, 3, 2, 2, 2, 4, 2, 12, 1, 2, 2, 56, 2, 12, 2, 1, 6, 2, 2, 1, 2, 4, 2, 10, 2, 12, 2, 4, 6, 4, 2, 4, 1, 1, 6, 2, 2, 12, 2, 8, 2, 2, 2, 24, 2, 4, 2, 1, 2, 12, 2, 2, 6, 4, 2, 3, 2, 2, 2, 4, 2, 12, 2, 2, 1, 2, 2, 56, 2, 4, 6, 4, 2, 18, 14, 8, 2, 4, 10, 12, 2, 1, 6, 1, 2, 12, 2, 2, 6

Offset: 1

Author

Antti Karttunen, May 21 2019

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A009194, A033879, A325385, A325635, A325637 (n such that a(n) = 2n).

Programs

PARI

A325636(n) = gcd(n+n,sigma(n));

Formula

a(n) = gcd(2n, A000203(n)).

a(n) = gcd(2n, A033879(n)) = gcd(sigma(n), A033879(n)).