A031259 a(n)=least k such that base 5 representation of n begins at s(k), where s=A031253.

1, 6, 2, 8, 3, 32, 5, 1, 7, 39, 6, 42, 11, 45, 13, 2, 15, 12, 17, 54, 19, 8, 21, 18, 23, 3, 26, 205, 29, 188, 32, 238, 35, 242, 38, 5, 41, 10, 44, 254, 1, 258, 50, 262, 53, 243, 7, 20, 59, 274, 39, 278, 65, 282, 28, 240, 9, 290, 6, 294, 42, 298