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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.

A318269 a(n) is the number of configurations of n indistinguishable pairs placed on the vertices of the ladder graph P_2 X P_n such that all but 4 such pairs are joined by an edge.

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 21
5 347
6 2919
7 17050
8 78815
9 309075
10 1072617
11 3386970
12 9921030
13 27338000
14 71614370
15 179788174
16 435311905
17 1021684125
18 2333955085
19 5207067714
20 11377225161
21 24403026561
22 51484962205
23 107024887620
24 219528748908
25 444886466640
26 891735024852
27 1769575953980

List of values

[0, 0, 0, 0, 21, 347, 2919, 17050, 78815, 309075, 1072617, 3386970, 9921030, 27338000, 71614370, 179788174, 435311905, 1021684125, 2333955085, 5207067714, 11377225161, 24403026561, 51484962205, 107024887620, 219528748908, 444886466640, 891735024852, 1769575953980]

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

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