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A044123 Numbers n such that string 3,3 occurs in the base 6 representation of n but not of n-1. 1

%I

%S 21,57,93,126,165,201,237,273,309,342,381,417,453,489,525,558,597,633,

%T 669,705,741,756,813,849,885,921,957,990,1029,1065,1101,1137,1173,

%U 1206,1245,1281,1317,1353,1389,1422,1461,1497,1533,1569,1605,1638,1677,1713

%N Numbers n such that string 3,3 occurs in the base 6 representation of n but not of n-1.

%t f[n_] := Length[StringPosition[ToString[FromDigits[IntegerDigits[n, 6]]], "33", 1]]; Select[Table[n, {n, 10000}], f[#] > 0 && f[# - 1] == 0 &] (* _Vladimir Joseph Stephan Orlovsky_, Jul 20 2011 *)

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,6],{3,3}]>0,1,0],{n,2000}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 14 2017 *)

%Y Cf. A044504.

%K nonn,base

%O 1,1

%A _Clark Kimberling_

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Last modified May 24 22:34 EDT 2022. Contains 354047 sequences. (Running on oeis4.)