%I
%S 20,120,209,220,320,420,520,620,720,820,920,1020,1120,1209,1220,1320,
%T 1420,1520,1620,1720,1820,1920,2099,2120,2209,2220,2320,2420,2520,
%U 2620,2720,2820,2920,3020,3120,3209,3220,3320,3420
%N Numbers n such that string 2,0 occurs in the base 10 representation of n but not of n+1.
%t Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{2,0}]>0,1,0],{n,3500}],{1,0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* _Harvey P. Dale_, Aug 05 2016 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
