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A263778

Number of inversion sequences avoiding pattern 120.

1, 1, 2, 6, 23, 103, 515, 2803, 16334, 100700, 650905, 4380595, 30528410, 219352058, 1619260140, 12245357074, 94636062782, 745907086918, 5985448211508, 48824435255942, 404330087326924, 3395418226577756, 28884708430087203, 248696210256230427

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OFFSET

0,3

COMMENTS

Number of length n inversion sequences avoiding e_k < e_i < e_j for i<j<k. A length n inversion sequence e_1,e_2,...,e_n consists of nonnegative integers e_t <= t-1. - Alois P. Heinz, Dec 20 2016

LINKS

Jay Pantone, Table of n, a(n) for n = 0..200

Nathan Britt and Nicholas Beaton, Completing the enumeration of inversion sequences avoiding triples of relations, arXiv:2512.21943 [math.CO], 2025. See p. 3, Table 1.

Sylvie Corteel, Megan A. Martinez, Carla D. Savage, and Michael Weselcouch, Patterns in Inversion Sequences I, arXiv:1510.05434 [math.CO], 2015.

Toufik Mansour and Mark Shattuck, Pattern Avoidance in Inversion Sequences, Pure Math. Appl. (PU.M.A.) 25 (2015), no. 2, 157-176.

Megan A. Martinez and Carla D. Savage, Patterns in Inversion Sequences II: Inversion Sequences Avoiding Triples of Relations, arXiv:1609.08106 [math.CO], 2016.

Jay Pantone, The enumeration of inversion sequences avoiding the patterns 201 and 210, arXiv:2310.19632 [math.CO], 2023.

Benjamin Testart, Completing the enumeration of inversion sequences avoiding one or two patterns of length 3, arXiv:2407.07701 [math.CO], 2024. See p. 2.

CROSSREFS

Cf. A263777, A263779, A263780.

Sequence in context: A061552 A338752 A374547 * A352854 A378608 A053488

Adjacent sequences: A263775 A263776 A263777 * A263779 A263780 A263781

KEYWORD

nonn

AUTHOR

Michel Marcus, Oct 26 2015

EXTENSIONS

a(0)=1 prepended by Alois P. Heinz, Dec 15 2016

a(10)-a(23) from Alois P. Heinz, Dec 20 2016

STATUS

approved

URL: https://oeis.org/A263778

⇱ A263778 - OEIS