A025728 Index of 8^n within sequence of numbers of form 3^i*8^j.

1, 3, 7, 13, 21, 31, 43, 57, 73, 91, 110, 131, 154, 179, 206, 235, 266, 299, 334, 370, 408, 448, 490, 534, 580, 628, 678, 730, 783, 838, 895, 954, 1015, 1078, 1143, 1210, 1279, 1350, 1422, 1496, 1572, 1650, 1730, 1812, 1896, 1982, 2070, 2159, 2250, 2343, 2438