A043139 - OEIS

%I #10 Aug 22 2021 20:50:23

%S 11,29,60,77,109,127,158,176,203,225,256,274,305,323,354,372,403,420,

%T 452,470,501,519,539,599,617,648,666,697,715,746,763,795,813,844,862,

%U 889,911,942,960,991,1009,1040,1058,1089,1106

%N Numbers k such that 1 and 4 occur juxtaposed in the base-7 representation of k but not of k-1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{1,4}]>0 || SequenceCount[IntegerDigits[n,7],{4,1}]>0,1,0],{n,1200}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 04 2020 *)

%Y Cf. A007093.

%K nonn,base

%O 1,1

%A _Clark Kimberling_