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%I #7 Nov 19 2019 17:16:48
%S 35,135,235,335,350,435,535,635,735,835,935,1035,1135,1235,1335,1350,
%T 1435,1535,1635,1735,1835,1935,2035,2135,2235,2335,2350,2435,2535,
%U 2635,2735,2835,2935,3035,3135,3235,3335,3350,3435
%N Numbers n such that string 3,5 occurs in the base 10 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{3,5}]>0,1,0],{n,3500}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 19 2019 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_