A354527 - OEIS

A354527

a(n) = A001221(n) - A354512(n).

0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 2, 0, 0, 0, 1, 0, 2, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 1, 1, 0, 2, 0, 1, 0, 1, 0, 2, 0, 2, 0, 1, 0, 2, 0, 1, 1, 1, 0, 3, 0, 0, 1, 1, 1, 2, 0, 1, 0, 2, 0, 2, 0, 1, 1, 1, 0, 1, 0, 2, 1, 1, 0, 3, 0, 1, 1, 1, 0, 3, 0

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OFFSET

1,12

COMMENTS

Number of distinct prime factors p of n such that gpf(n+p) != p, gpf = A006530.

Number of distinct prime factors p of n such that n+p is not p-smooth.

LINKS

Jianing Song, Table of n, a(n) for n = 1..10000

EXAMPLE

a(30) = 2 since the prime factors of 30 are 2,3,5, and we have gpf(30+3) != 3 and gpf(30+5) != 5.

PROG

(PARI) gpf(n) = vecmax(factor(n)[, 1]);