A044352 Numbers n such that string 2,0 occurs in the base 10 representation of n but not of n-1.

20, 120, 200, 220, 320, 420, 520, 620, 720, 820, 920, 1020, 1120, 1200, 1220, 1320, 1420, 1520, 1620, 1720, 1820, 1920, 2000, 2120, 2200, 2220, 2320, 2420, 2520, 2620, 2720, 2820, 2920, 3020, 3120, 3200, 3220, 3320, 3420

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base
• easy

Comments

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

Links

• Index entries for 10-automatic sequences

Crossrefs

Subsequence of A121040.

Programs

Mathematica

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 *)