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A336352
Number of prime divisors of sigma(n) that are larger than the largest prime factor of n; a(1) = 0.
9
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
1,8
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).
Sequence in context: A304685 A186714 A160382 * A081221 A366988 A280827
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 19 2020
STATUS
approved