A025631 Numbers of form 7^i*9^j, with i, j >= 0.

1, 7, 9, 49, 63, 81, 343, 441, 567, 729, 2401, 3087, 3969, 5103, 6561, 16807, 21609, 27783, 35721, 45927, 59049, 117649, 151263, 194481, 250047, 321489, 413343, 531441, 823543, 1058841, 1361367, 1750329, 2250423, 2893401, 3720087, 4782969