a(n)=least k such that base 5 representation of n begins at s(k), where s=A031235.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =14a(5) =6a(6) =1a(7) =10a(8) =12a(9) =24a(10) =9a(11) =18a(12) =2a(13) =22a(14) =34a(15) =11a(16) =21a(17) =30a(18) =3a(19) =4a(20) =13a(21) =23a(22) =33a(23) =42a(24) =119a(25) =48a(26) =14a(27) =89a(28) =104a(29) =47