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.

A258392 Number of 2n-length strings of balanced parentheses of exactly 4 different types that are introduced in ascending order.

Table of values

n a(n)
4 14
5 420
6 8580
7 150150
8 2432430
9 37777740
10 572827580
11 8568059500
12 127199546012
13 1881416537000
14 27792098497800
15 410634370077750
16 6074408847920670
17 90017212151219100
18 1336818529866319500
19 19898794932394570500
20 296909055625560798420
21 4440849374395184751000

List of values

[14, 420, 8580, 150150, 2432430, 37777740, 572827580, 8568059500, 127199546012, 1881416537000, 27792098497800, 410634370077750, 6074408847920670, 90017212151219100, 1336818529866319500, 19898794932394570500, 296909055625560798420, 4440849374395184751000]

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

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