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A144765
Number of triprimes less than or equal to and not coprime to n.
0
0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 2, 0, 2, 1, 2, 0, 3, 0, 4, 2, 4, 0, 4, 1, 4, 3, 5, 0, 7, 0, 6, 4, 6, 3, 7, 0, 6, 4, 6, 0, 8, 0, 8, 7, 8, 0, 10, 2, 10, 6, 10, 0, 12, 5, 10, 6, 10, 0, 12, 0, 10, 8, 10, 5, 14, 0, 12, 8, 15, 0, 16, 0, 13, 12, 14, 6, 19, 0, 17, 10, 15, 0, 19, 7, 15, 10, 15, 0, 19, 6, 16
OFFSET
1,12
PROG
(PARI) a(n) = sum(k=1, n, if (bigomega(k) == 3, gcd(k, n) != 1)); \\ Michel Marcus, Apr 15 2023
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Reikku Kulon, Sep 20 2008
STATUS
approved