A043947 - OEIS

%I #11 Aug 26 2021 03:17:01

%S 21,42,85,106,149,175,213,234,277,298,343,362,405,426,469,490,533,554,

%T 597,618,661,687,725,746,789,810,855,874,917,938,981,1002,1045,1066,

%U 1109,1130,1173,1199,1237,1258,1301,1322,1407

%N Numbers k such that 2 and 5 occur juxtaposed in the base-8 representation of k but not of k+1.

%t Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n,8],{2,5}]>0||SequenceCount[IntegerDigits[n,8],{5,2}]>0,1,0],{n,1500}],{1,0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* _Harvey P. Dale_, Jul 19 2016 *)

%Y Cf. A007094.

%K nonn,base

%O 1,1

%A _Clark Kimberling_