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%I #7 Apr 11 2020 17:16:45
%S 70,170,270,370,470,570,670,700,770,870,970,1070,1170,1270,1370,1470,
%T 1570,1670,1700,1770,1870,1970,2070,2170,2270,2370,2470,2570,2670,
%U 2700,2770,2870,2970,3070,3170,3270,3370,3470,3570
%N Numbers n such that string 7,0 occurs in the base 10 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{7,0}]>0,1,0],{n,3600}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 11 2020 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_