%I
%S 24,73,122,168,220,269,318,367,416,465,511,563,612,661,710,759,808,
%T 854,906,955,1004,1053,1102,1151,1176,1249,1298,1347,1396,1445,1494,
%U 1540,1592,1641,1690,1739,1788,1837,1883,1935,1984
%N Numbers n such that string 3,3 occurs in the base 7 representation of n but not of n1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{3,3}]>0,1,0],{n,2000}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jan 06 2019 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
