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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.

A305625 Number of chiral pairs of rows of n colors with exactly 5 different colors.

Table of values

n a(n)
1 0
2 0
3 0
4 0
5 60
6 900
7 8400
8 63000
9 417000
10 2551440
11 14802900
12 82763100
13 450501660
14 2404493700
15 12645952200
16 65771370000
17 339164682000
18 1737485315640
19 8855354531100
20 44952362878500
21 227475739300260
22 1148269299919500
23 5785013208282000
24 29100046926951000
25 146201097996135000
26 733811769167043840
27 3680292427100043300
28 18446421887430345900
29 92412024657725026860
30 462780012983867889300
31 2316780309783100387800

List of values

[0, 0, 0, 0, 60, 900, 8400, 63000, 417000, 2551440, 14802900, 82763100, 450501660, 2404493700, 12645952200, 65771370000, 339164682000, 1737485315640, 8855354531100, 44952362878500, 227475739300260, 1148269299919500, 5785013208282000, 29100046926951000, 146201097996135000, 733811769167043840, 3680292427100043300, 18446421887430345900, 92412024657725026860, 462780012983867889300, 2316780309783100387800]

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

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