A065371 a(1) = 1, a(prime(i)) = prime(i) - i for i > 0 and a(u * v) = a(u) * a(v) for u, v > 0.

1, 1, 1, 1, 2, 1, 3, 1, 1, 2, 6, 1, 7, 3, 2, 1, 10, 1, 11, 2, 3, 6, 14, 1, 4, 7, 1, 3, 19, 2, 20, 1, 6, 10, 6, 1, 25, 11, 7, 2, 28, 3, 29, 6, 2, 14, 32, 1, 9, 4, 10, 7, 37, 1, 12, 3, 11, 19, 42, 2, 43, 20, 3, 1, 14, 6, 48, 10, 14, 6, 51, 1, 52, 25, 4, 11, 18, 7, 57, 2, 1, 28, 60, 3, 20, 29