A336352 - OEIS

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

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OFFSET

1,8

LINKS

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

Index entries for sequences related to sigma(n)

FORMULA

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

PROG

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

CROSSREFS

Cf. A000203, A006530, A058062, A336353 (positions of zeros).