A030406 a(n)=least k such that base 4 representation of n begins at s(k), where s=A030401.

1, 7, 2, 15, 3, 8, 1, 39, 7, 51, 9, 63, 2, 6, 10, 87, 15, 103, 18, 17, 3, 29, 4, 41, 27, 53, 8, 65, 1, 5, 12, 215, 39, 231, 42, 247, 28, 7, 48, 279, 51, 295, 54, 311, 31, 55, 9, 343, 63, 359, 66, 14, 2, 26, 11, 38, 6, 50, 56, 62, 10, 37, 61, 471