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

Offset: 0

Author

Michel Marcus, Oct 26 2015

Keywords

• nonn

Comments

Number of length n inversion sequences avoiding e_k < e_i < e_j for iAlois P. Heinz, Dec 20 2016

Links

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

Extensions

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

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