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%I #7 May 31 2016 11:00:07
%S 48,97,146,195,244,293,336,391,440,489,538,587,636,679,734,783,832,
%T 881,930,979,1022,1077,1126,1175,1224,1273,1322,1365,1420,1469,1518,
%U 1567,1616,1665,1708,1763,1812,1861,1910,1959,2008
%N Numbers n such that string 6,6 occurs in the base 7 representation of n but not of n-1.
%t Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{6,6}]>0,1,0],{n,2100}],{0,1}]][[2]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* _Harvey P. Dale_, May 31 2016 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_