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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.

A307304 Number of inequivalent ways of placing 2 nonattacking rooks on n X n board up to rotations and reflections of the board.

Table of values

n a(n)
1 0
2 1
3 4
4 13
5 31
6 66
7 123
8 214
9 346
10 535
11 790
12 1131
13 1569
14 2128
15 2821
16 3676
17 4708
18 5949
19 7416
20 9145
21 11155
22 13486
23 16159
24 19218
25 22686
26 26611
27 31018
28 35959
29 41461
30 47580
31 54345
32 61816
33 70024
34 79033
35 88876
36 99621
37 111303
38 123994
39 137731
40 152590
41 168610
42 185871

List of values

[0, 1, 4, 13, 31, 66, 123, 214, 346, 535, 790, 1131, 1569, 2128, 2821, 3676, 4708, 5949, 7416, 9145, 11155, 13486, 16159, 19218, 22686, 26611, 31018, 35959, 41461, 47580, 54345, 61816, 70024, 79033, 88876, 99621, 111303, 123994, 137731, 152590, 168610, 185871]

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

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