%I #10 Aug 22 2021 22:16:00
%S 17,23,66,72,115,119,161,170,213,219,262,268,311,317,360,366,409,415,
%T 458,462,504,513,556,562,605,611,654,660,703,709,752,758,801,805,833,
%U 899,905,948,954,997,1003,1046,1052,1095,1101
%N Numbers k such that 2 and 3 occur juxtaposed in the base-7 representation of k but not of k-1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{2,3}]>0 || SequenceCount[IntegerDigits[n,7],{3,2}]>0,1,0],{n,1200}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 26 2017 *)
%Y Cf. A007093.
%K nonn,base
%O 1,1
%A _Clark Kimberling_
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