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A324474 Nonzero ternary words such that any non-initial 1 is preceded by 0, and any non-initial 2 is preceded by 00. 2
1, 2, 10, 20, 100, 101, 200, 201, 1000, 1001, 1002, 1010, 2000, 2001, 2002, 2010, 10000, 10001, 10002, 10010, 10020, 10100, 10101, 20000, 20001, 20002, 20010, 20020, 20100, 20101, 100000, 100001, 100002, 100010, 100020, 100100, 100101, 100200, 100201 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This could have begun with an initial 0, but (since this is a list, and must have offset 1), we would no longer have a(1)=1, and that is needed for some related sequences.

The indices of words of the form 100...00 are 1, 3, 5, 9, 17, 31, ..., see the tribonacci numbers A000213.

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..845

EXAMPLE

The initial terms, as a list:

1

2

10

20

100

101

200

201

1000

1001

1002

1010

2000

2001

2002

2010

10000

...

CROSSREFS

Cf. A007089, A324475, A000213.

Sequence in context: A164882 A029994 A298411 * A294493 A261660 A004643

Adjacent sequences:  A324471 A324472 A324473 * A324475 A324476 A324477

KEYWORD

nonn,base

AUTHOR

Nathan Fox and N. J. A. Sloane, Mar 09 2019

STATUS

approved

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Last modified July 25 03:36 EDT 2021. Contains 346282 sequences. (Running on oeis4.)