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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.

A318268 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 3 such pairs are joined by an edge.

Table of values

n a(n)
0 0
1 0
2 0
3 2
4 34
5 250
6 1234
7 4830
8 16174
9 48444
10 133416
11 344220
12 843020
13 1978804
14 4484228
15 9865742
16 21166390
17 44439910
18 91570126
19 185614242
20 370846914
21 731502296
22 1426514540
23 2753525208
24 5266164280
25 9987859912
26 18799814312
27 35141997050
28 65274659562
29 120540177522

List of values

[0, 0, 0, 2, 34, 250, 1234, 4830, 16174, 48444, 133416, 344220, 843020, 1978804, 4484228, 9865742, 21166390, 44439910, 91570126, 185614242, 370846914, 731502296, 1426514540, 2753525208, 5266164280, 9987859912, 18799814312, 35141997050, 65274659562, 120540177522]

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

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