A043151 - OEIS

%I #10 Aug 22 2021 22:36:46

%S 41,47,90,96,139,145,188,194,237,243,286,329,341,384,390,433,439,482,

%T 488,531,537,580,586,629,672,684,727,733,776,782,825,831,874,880,923,

%U 929,972,1015,1027,1070,1076,1119,1125,1168,1174

%N Numbers k such that 5 and 6 occur juxtaposed in the base-7 representation of k but not of k-1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,7],{5,6}]>0 || SequenceCount[IntegerDigits[n,7],{6,5}]>0,1,0],{n,1200}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 23 2021 *)

%Y Cf. A007093.

%K nonn,base

%O 1,1

%A _Clark Kimberling_