Least k such that S(k) = S(k+n), or 0 if there is no k, where S is the Kempner function A002034.

Terms

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