A044352 - OEIS

%I #11 Apr 18 2020 01:46:36

%S 20,120,200,220,320,420,520,620,720,820,920,1020,1120,1200,1220,1320,

%T 1420,1520,1620,1720,1820,1920,2000,2120,2200,2220,2320,2420,2520,

%U 2620,2720,2820,2920,3020,3120,3200,3220,3320,3420

%N Numbers n such that string 2,0 occurs in the base 10 representation of n but not of n-1.

%C This is a (thin) subsequence of the terms of A121040 ending with a 2 followed by one or more zeros and which do not otherwise contain a 2 followed by a 0. This also demonstrates that this sequence is a 10-automatic. - _Charles R Greathouse IV_, Apr 18 2020

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>

%t SequencePosition[Table[If[SequenceCount[IntegerDigits[n],{2,0}]>0,1,0],{n,3500}],{0,1}][[All,2]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 24 2018 *)

%Y Subsequence of A121040.

%K nonn,base,easy

%O 1,1

%A _Clark Kimberling_