A336352 Number of prime divisors of sigma(n) that are larger than the largest prime factor of n; a(1) = 0.

0, 1, 0, 1, 0, 0, 0, 2, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 2, 0, 0, 0, 0, 0

Offset: 1

Author

Antti Karttunen, Jul 19 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, A006530, A058062, A336353 (positions of zeros).

Programs

PARI

A336352(n) = if(1==n,0,my(gp=vecmax(factor(n)[, 1])); #select(p -> (p>gp), factor(sigma(n))[, 1]));

Formula

For all n >= 1, a(n) <= A058062(n).