A031225 a(n)=least k such that base 5 representation of n begins at s(k), where s=A031219.

1, 2, 3, 4, 5, 7, 1, 11, 13, 15, 10, 19, 2, 23, 25, 12, 22, 31, 3, 35, 4, 14, 24, 34, 45, 5, 51, 54, 57, 50, 7, 8, 69, 72, 75, 9, 18, 1, 87, 90, 11, 28, 99, 102, 105, 73, 13, 114, 117, 120, 76, 15, 129, 132, 53, 68, 17, 10, 113, 128, 82, 19, 20