A043991 - OEIS

%I #11 Aug 27 2021 01:45:20

%S 52,68,133,149,214,230,295,311,376,392,457,476,538,554,620,635,700,

%T 716,781,797,862,878,943,959,1024,1040,1105,1121,1186,1205,1267,1283,

%U 1349,1364,1429,1445,1510,1526,1591,1607,1672,1688

%N Numbers k such that 5 and 7 occur juxtaposed in the base-9 representation of k but not of k+1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n,9],{5,7}]>0 || SequenceCount[ IntegerDigits[n,9],{7,5}]>0,1,0],{n,2000}],{1,0}][[All,1]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jan 23 2019 *)

%Y Cf. A007095.

%K nonn,base

%O 1,1

%A _Clark Kimberling_