# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a043949 Showing 1-1 of 1 %I A043949 #12 Aug 26 2021 03:16:40 %S A043949 23,58,87,122,151,191,215,250,279,314,343,378,407,442,471,506,535,570, %T A043949 599,634,663,703,727,762,791,826,855,890,919,954,983,1018,1047,1082, %U A043949 1111,1146,1175,1215,1239,1274,1303,1338,1367 %N A043949 Numbers k such that 2 and 7 occur juxtaposed in the base-8 representation of k but not of k+1. %t A043949 s27Q[n_]:=Module[{idn8=IntegerDigits[n,8]},If[SequenceCount[idn8, {2,7}]> 0 ||SequenceCount[idn8,{7,2}]>0,1,0]]; Transpose[ SequencePosition[ Table[ s27Q[n],{n,1400}],{1,0}]][[1]] (* The program uses the SequenceCount and SequencePosition functions from Mathematica version 10 *) (* _Harvey P. Dale_, Oct 10 2015 *) %Y A043949 Cf. A007094. %K A043949 nonn,base %O A043949 1,1 %A A043949 _Clark Kimberling_ # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE