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%I #7 May 05 2020 13:18:16
%S 25,89,153,207,217,281,345,409,473,537,601,665,719,729,793,857,921,
%T 985,1049,1113,1177,1231,1241,1305,1369,1433,1497,1561,1663,1689,1743,
%U 1753,1817,1881,1945,2009,2073,2137,2201,2255,2265
%N Numbers n such that string 3,1 occurs in the base 8 representation of n but not of n+1.
%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{3,1}]>0,1,0],{n,2500}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 05 2020 *)
%K nonn,base
%O 1,1
%A _Clark Kimberling_