%I #7 Apr 08 2019 16:30:31
%S 78,159,240,321,402,483,564,645,702,726,807,888,969,1050,1131,1212,
%T 1293,1374,1431,1455,1536,1617,1698,1779,1860,1941,2022,2103,2160,
%U 2184,2265,2346,2427,2508,2589,2670,2751,2832,2889
%N Numbers n such that string 8,6 occurs in the base 9 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,9],{8,6}]>0,1,0],{n,3000}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 08 2019 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_