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%I #10 Jan 28 2020 17:02:00
%S 66,147,228,309,390,471,552,594,633,714,795,876,957,1038,1119,1200,
%T 1281,1323,1362,1443,1524,1605,1686,1767,1848,1929,2010,2052,2091,
%U 2172,2253,2334,2415,2496,2577,2658,2739,2781,2820
%N Numbers n such that string 7,3 occurs in the base 9 representation of n but not of n-1.
%t Select[Range[3000],MemberQ[Partition[IntegerDigits[#,9],2,1],{7,3}] && !MemberQ[Partition[IntegerDigits[#-1,9],2,1],{7,3}]&] (* _Harvey P. Dale_, Sep 16 2011 *)
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,9],{7,3}]>0,1,0],{n,3000}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jan 28 2020 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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