cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A137591 Number of parenthesizings of products formed by n factors assuming nonassociativity and partial commutativity: individual factors commute, but bracketed expressions don't commute with anything.

Table of values

n a(n)
1 1
2 1
3 6
4 54
5 660
6 10260
7 194040
8 4326840
9 111177360
10 3234848400
11 105135861600
12 3775206204000
13 148426878600000
14 6341634955656000
15 292576856395824000
16 14496220038251952000
17 767691210706291872000
18 43274547687106768032000
19 2587028200730649643968000
20 163484729048197101504960000

List of values

[1, 1, 6, 54, 660, 10260, 194040, 4326840, 111177360, 3234848400, 105135861600, 3775206204000, 148426878600000, 6341634955656000, 292576856395824000, 14496220038251952000, 767691210706291872000, 43274547687106768032000, 2587028200730649643968000, 163484729048197101504960000]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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