A339964 a(n) = gcd(sigma(n), n+1).

1, 3, 4, 1, 6, 1, 8, 3, 1, 1, 12, 1, 14, 3, 8, 1, 18, 1, 20, 21, 2, 1, 24, 5, 1, 3, 4, 1, 30, 1, 32, 3, 2, 1, 12, 1, 38, 3, 8, 1, 42, 1, 44, 3, 2, 1, 48, 1, 1, 3, 4, 1, 54, 5, 8, 3, 2, 1, 60, 1, 62, 3, 8, 1, 6, 1, 68, 3, 2, 1, 72, 1, 74, 3, 4, 7, 6, 1, 80, 3, 1, 1, 84, 1, 2, 3, 8, 1, 90, 13, 4, 3, 2, 1, 24, 1, 98, 9, 4, 1, 102

Offset: 1

Author

Antti Karttunen, Dec 25 2020

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, A339965, A339966.

Cf. A339963 (positions of 2's).

Cf. also A049559, A062754.

Programs

PARI

A339964(n) = gcd(sigma(n),n+1);