%I #7 Mar 06 2020 19:25:14

%S 68,168,268,368,468,568,668,689,768,868,968,1068,1168,1268,1368,1468,

%T 1568,1668,1689,1768,1868,1968,2068,2168,2268,2368,2468,2568,2668,

%U 2689,2768,2868,2968,3068,3168,3268,3368,3468,3568

%N Numbers n such that string 6,8 occurs in the base 10 representation of n but not of n+1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{6,8}]>0,1,0],{n,4000}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 06 2020 *)

%K nonn,base

%O 1,1

%A _Clark Kimberling_