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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.

A304974 Number of achiral color patterns (set partitions) for a row or loop of length n using exactly 4 colors (sets).

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 1
5 2
6 9
7 16
8 53
9 90
10 265
11 440
12 1221
13 2002
14 5369
15 8736
16 22933
17 37130
18 96105
19 155080
20 397541
21 640002
22 1629529
23 2619056
24 6636213
25 10653370
26 26899145
27 43144920
28 108659461
29 174174002
30 437826489
31 701478976
32 1760871893
33 2820264810
34 7072185385
35 11324105960
36 28374834981
37 45425564002
38 113757620249

List of values

[0, 0, 0, 0, 1, 2, 9, 16, 53, 90, 265, 440, 1221, 2002, 5369, 8736, 22933, 37130, 96105, 155080, 397541, 640002, 1629529, 2619056, 6636213, 10653370, 26899145, 43144920, 108659461, 174174002, 437826489, 701478976, 1760871893, 2820264810, 7072185385, 11324105960, 28374834981, 45425564002, 113757620249]

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

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