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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.

A253192 Number of ways to place nonintersecting diagonals in convex (n+3)-gon so as to create exactly one triangle.

Table of values

n a(n)
0 1
1 0
2 5
3 6
4 35
5 80
6 309
7 890
8 3058
9 9580
10 31863
11 103054
12 340415
13 1116032
14 3688745
15 12176814
16 40344505
17 133742500
18 444262378
19 1477142040
20 4918099660
21 16390294664
22 54679621775
23 182572812266
24 610115196150
25 2040383498748
26 6828408179435
27 22866979920390
28 76623655367703
29 256899191586880
30 861774049296325

List of values

[1, 0, 5, 6, 35, 80, 309, 890, 3058, 9580, 31863, 103054, 340415, 1116032, 3688745, 12176814, 40344505, 133742500, 444262378, 1477142040, 4918099660, 16390294664, 54679621775, 182572812266, 610115196150, 2040383498748, 6828408179435, 22866979920390, 76623655367703, 256899191586880, 861774049296325]

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

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