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Numbers n such that string 7,2 occurs in the base 10 representation of n but not of n+1.
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%I #7 May 29 2016 09:28:30

%S 72,172,272,372,472,572,672,729,772,872,972,1072,1172,1272,1372,1472,

%T 1572,1672,1729,1772,1872,1972,2072,2172,2272,2372,2472,2572,2672,

%U 2729,2772,2872,2972,3072,3172,3272,3372,3472,3572

%N Numbers n such that string 7,2 occurs in the base 10 representation of n but not of n+1.

%t Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{7,2}]>0,1,0],{n,3600}],{1,0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* _Harvey P. Dale_, May 29 2016 *)

%K nonn,base

%O 1,1

%A _Clark Kimberling_