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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.

A278641 Number of pairs of orientable necklaces with n beads and up to 5 colors; i.e., turning the necklace over does not leave it unchanged. The turned-over necklace is not included in the count.

Table of values

n a(n)
0 0
1 0
2 0
3 10
4 45
5 252
6 1130
7 5270
8 23520
9 106960
10 483756
11 2211650
12 10149805
13 46911060
14 217868310
15 1017057518
16 4767797895
17 22438419120
18 105960938380
19 501928967930
20 2384171386941
21 11353241261180
22 54185968572450
23 259150507387910
24 1241763071712930
25 5960463867187752
26 28656077411358180
27 137973711706163210

List of values

[0, 0, 0, 10, 45, 252, 1130, 5270, 23520, 106960, 483756, 2211650, 10149805, 46911060, 217868310, 1017057518, 4767797895, 22438419120, 105960938380, 501928967930, 2384171386941, 11353241261180, 54185968572450, 259150507387910, 1241763071712930, 5960463867187752, 28656077411358180, 137973711706163210]

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

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