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%I #7 Apr 08 2020 12:41:37
%S 63,163,263,363,463,563,630,663,763,863,963,1063,1163,1263,1363,1463,
%T 1563,1630,1663,1763,1863,1963,2063,2163,2263,2363,2463,2563,2630,
%U 2663,2763,2863,2963,3063,3163,3263,3363,3463,3563
%N Numbers n such that string 6,3 occurs in the base 10 representation of n but not of n-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{6,3}]>0,1,0],{n,3600}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 08 2020 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_