A025735 Index of 9^n within sequence of numbers of form 5^i*9^j.

1, 3, 6, 11, 17, 24, 33, 43, 54, 67, 81, 97, 114, 132, 152, 173, 195, 219, 244, 270, 298, 327, 358, 390, 423, 458, 494, 531, 570, 610, 651, 694, 738, 784, 831, 879, 929, 980, 1032, 1086, 1141, 1197, 1255, 1314, 1375, 1437, 1500, 1565, 1631, 1698, 1767, 1837