A043228 - OEIS

%I #10 Aug 23 2021 21:45:22

%S 15,51,115,150,215,251,315,351,415,451,510,551,615,651,715,751,815,

%T 851,915,951,1015,1051,1115,1150,1215,1251,1315,1351,1415,1451,1500,

%U 1615,1651,1715,1751,1815,1851,1915,1951,2015,2051

%N Numbers k such that 1 and 5 occur juxtaposed in the base-10 representation of k but not of k-1.

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{1,5}]>0 || SequenceCount[ IntegerDigits[n],{5,1}]>0,1,0],{n,2100}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 15 2020 *)

%K nonn,base

%O 1,1

%A _Clark Kimberling_