A043913 - OEIS

%I #10 Aug 25 2021 05:03:38

%S 21,52,70,101,119,153,168,199,217,248,266,297,315,346,370,395,413,444,

%T 462,496,511,542,560,591,609,640,658,689,713,738,756,787,805,839,854,

%U 885,903,934,952,983,1001,1077,1081,1099,1130

%N Numbers k such that 0 and 3 occur juxtaposed in the base-7 representation of k but not of k+1.

%t jQ[n_]:=Module[{idn7=IntegerDigits[n,7]},Max[SequenceCount[idn7,{0,3}],SequenceCount[idn7,{3,0}]]>0]; Transpose[ SequencePosition[ Table[ If[ jQ[n],1,0],{n,1200}],{1,0}]][[1]] (* The program uses the SequenceCount and SequencePosition functions from Mathematica version 10 *) (* _Harvey P. Dale_, Oct 26 2015 *)

%Y Cf. A007093.

%K nonn,base

%O 1,1

%A _Clark Kimberling_