A144764 Partial totient function phi(c, n) for c = 3: number of 3-semiprimes less than and coprime to n.
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 2, 0, 1, 0, 2, 0, 3, 0, 2, 0, 4, 0, 3, 0, 2, 1, 6, 0, 7, 1, 3, 1, 4, 0, 7, 1, 3, 1, 7, 0, 8, 1, 3, 2, 10, 0, 8, 1, 5, 2, 12, 0, 7, 2, 6, 2, 12, 0, 12, 2, 5, 3, 8, 0, 14, 3, 7, 1, 16, 0, 16, 3, 5, 4, 12, 0, 19, 2, 9, 4, 19, 0, 12, 4, 9, 4, 19, 0, 13, 4, 10, 4, 13, 0, 20, 3
Offset: 1