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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.)