A025642 Exponent of 3 (value of i) in n-th number of form 3^i*7^j.

0, 1, 0, 2, 1, 3, 0, 2, 4, 1, 3, 5, 0, 2, 4, 6, 1, 3, 5, 7, 0, 2, 4, 6, 8, 1, 3, 5, 7, 0, 9, 2, 4, 6, 8, 1, 10, 3, 5, 7, 0, 9, 2, 11, 4, 6, 8, 1, 10, 3, 12, 5, 7, 0, 9, 2, 11, 4, 13, 6, 8, 1, 10, 3, 12, 5, 14, 7, 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12, 5, 14, 7, 0, 16, 9, 2, 11, 4, 13, 6, 15, 8, 1, 17, 10