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A354527
a(n) = A001221(n) - A354512(n).
4
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
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
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]);
a(n) = my(f=factor(n)[, 1]); sum(i=1, #f, gpf(n+f[i])!=f[i])
CROSSREFS
Cf. A354525 (indices of 0), A354526 (indices of positive terms).
Sequence in context: A070201 A070138 A024153 * A341523 A079127 A056674
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 16 2022
STATUS
approved