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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.

A368815 Number of edges in a regular 2n-gon when all vertices are connect by straight lines except for the n lines joining diametrically opposite vertices.

Table of values

n a(n)
1 0
2 4
3 24
4 104
5 320
6 648
7 1540
8 2832
9 3996
10 7860
11 12100
12 15552
13 25376
14 35084
15 36840
16 62752
17 81600
18 97272
19 131556
20 163720
21 178332
22 245564
23 296516
24 336960
25 421600
26 497172
27 557280
28 678552
29 786016
30 836520
31 1038500
32 1185344
33 1301124
34 1525444
35 1720740
36 1893600
37 2166720
38 2419612
39 2628600
40 2991440

List of values

[0, 4, 24, 104, 320, 648, 1540, 2832, 3996, 7860, 12100, 15552, 25376, 35084, 36840, 62752, 81600, 97272, 131556, 163720, 178332, 245564, 296516, 336960, 421600, 497172, 557280, 678552, 786016, 836520, 1038500, 1185344, 1301124, 1525444, 1720740, 1893600, 2166720, 2419612, 2628600, 2991440]

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

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