The On-Line Encyclopedia of Integer Sequences (OEIS)

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A279558

Number of length n inversion sequences avoiding the patterns 010, 120, and 210.
(history; published version)

#2 by Megan A. Martinez at Tue Jan 17 10:23:02 EST 2017

NAME

allocated for Megan A. Martinez

Number of length n inversion sequences avoiding the patterns 010, 120, and 210.

DATA

1, 1, 2, 5, 15, 52, 200, 830, 3654, 16869

OFFSET

0,3

COMMENTS

A length n inversion sequence e_1e_2...e_n is a sequence of integers where 0 <= e_i <= i-1. The term a(n) counts those length n inversion sequences with no entries e_i, e_j, e_k (where i<j<k) such that e_i <> e_j > e_k and e_i >= e_k. This is the same as the set of length n inversion sequences avoiding 010, 120, and 210.

LINKS

Megan A. Martinez, Carla D. Savage, <a href="https://arxiv.org/abs/1609.08106">Patterns in Inversion Sequences II: Inversion Sequences Avoiding Triples of Relations</a>, arXiv:1609.08106 [math.CO], 2016.

EXAMPLE

The length 4 inversion sequences avoiding (010, 120, 210) are 0000, 0001, 0002, 0003, 0011, 0012, 0013, 0021, 0022, 0023, 0111, 0112, 0113, 0122, 0123.

CROSSREFS

Cf. A000108, A263777, A263778, A263779, A263780, A279551, A279552, A279553, A279554, A279555, A279556, A279557, A279559, A279560, A279561, A279562, A279563, A279564, A279565, A279566, A279567, A279568, A279569, A279570, A279571, A279572, A279573.

KEYWORD

allocated

nonn,more

AUTHOR

Megan A. Martinez, Jan 17 2017

STATUS

approved