%I
%S 39,88,137,186,235,279,284,333,382,431,480,529,578,622,627,676,725,
%T 774,823,872,921,965,970,1019,1068,1117,1166,1215,1264,1308,1313,1362,
%U 1411,1460,1509,1558,1607,1651,1656,1705,1754,1803
%N Numbers n such that string 5,4 occurs in the base 7 representation of n but not of n+1.
%t Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{5,4}]>0,1,0],{n,2000}],{1,0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* _Harvey P. Dale_, Jun 05 2016 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
