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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.

A185100 Dihedral unlabeled Motzkin numbers: number of ways of drawing any number of nonintersecting chords joining n unlabeled points equally spaced on a circle, up to rotations and reflections of the circle.

Table of values

n a(n)
0 1
1 1
2 2
3 2
4 4
5 5
6 11
7 16
8 36
9 65
10 150
11 312
12 756
13 1743
14 4353
15 10732
16 27489
17 70379
18 183866
19 481952
20 1277784
21 3402661
22 9126689
23 24584870
24 66567924
25 180939737
26 493801694
27 1352203202
28 3715137460
29 10237545525
30 28291018283
31 78384998904
32 217715672036
33 606103034821
34 1691020991782
35 4727601528674
36 13242641322252
37 37162431389051
38 104469244613429

List of values

[1, 1, 2, 2, 4, 5, 11, 16, 36, 65, 150, 312, 756, 1743, 4353, 10732, 27489, 70379, 183866, 481952, 1277784, 3402661, 9126689, 24584870, 66567924, 180939737, 493801694, 1352203202, 3715137460, 10237545525, 28291018283, 78384998904, 217715672036, 606103034821, 1691020991782, 4727601528674, 13242641322252, 37162431389051, 104469244613429]

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

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