A044358 - OEIS

A044358

Numbers n such that string 2,6 occurs in the base 10 representation of n but not of n-1.

%I #13 Jul 03 2021 11:46:11

%S 26,126,226,260,326,426,526,626,726,826,926,1026,1126,1226,1260,1326,

%T 1426,1526,1626,1726,1826,1926,2026,2126,2226,2260,2326,2426,2526,

%U 2600,2726,2826,2926,3026,3126,3226,3260,3326,3426

%N Numbers n such that string 2,6 occurs in the base 10 representation of n but not of n-1.

%H Vincenzo Librandi, <a href="/A044358/b044358.txt">Table of n, a(n) for n = 1..5000</a>

%t Select[Range[4000],MemberQ[Partition[IntegerDigits[#],2,1],{2,6}] && !MemberQ[Partition[IntegerDigits[#-1],2,1],{2,6}]&] (* _Harvey P. Dale_, Mar 20 2012 *)

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{2,6}]>0,1,0],{n,3500}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 03 2021 *)

%K nonn,base

%O 1,1

%A _Clark Kimberling_