A043208 - OEIS

%I #11 Aug 23 2021 06:36:53

%S 43,67,124,148,205,229,286,310,367,387,448,472,529,553,603,634,691,

%T 715,772,796,853,877,934,958,1015,1039,1096,1116,1177,1201,1258,1282,

%U 1332,1363,1420,1444,1501,1525,1582,1606,1663,1687

%N Numbers k such that 4 and 7 occur juxtaposed in the base-9 representation of k but not of k-1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,9],{4,7}]>0 || SequenceCount[IntegerDigits[n,9],{7,4}]>0,1,0],{n,2000}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 28 2018 *)

%Y Cf. A007095.

%K nonn,base

%O 1,1

%A _Clark Kimberling_