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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.

A305624 Number of chiral pairs of rows of n colors with exactly 4 different colors.

Table of values

n a(n)
1 0
2 0
3 0
4 12
5 120
6 780
7 4188
8 20400
9 93120
10 409140
11 1748220
12 7337232
13 30386160
14 124696740
15 508250988
16 2061566400
17 8331954240
18 33585590580
19 135115594140
20 542784981552
21 2178107091600
22 8733341736900
23 34996103558988
24 140172672276000
25 561255446475360
26 2246716252964820
27 8991948337723260
28 35983044114659472
29 143977928423467440
30 576048972752188260
31 2304607666801990188
32 9219666007300387200
33 36882370043723748480

List of values

[0, 0, 0, 12, 120, 780, 4188, 20400, 93120, 409140, 1748220, 7337232, 30386160, 124696740, 508250988, 2061566400, 8331954240, 33585590580, 135115594140, 542784981552, 2178107091600, 8733341736900, 34996103558988, 140172672276000, 561255446475360, 2246716252964820, 8991948337723260, 35983044114659472, 143977928423467440, 576048972752188260, 2304607666801990188, 9219666007300387200, 36882370043723748480]

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

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