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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.

A265451 Number of n X 1 0..n+1-2 arrays with each element differing from its horizontal and vertical neighbors by one or two.

Table of values

n a(n)
0 1
1 1
2 2
3 12
4 66
5 360
6 1864
7 9358
8 45642
9 217590
10 1017626
11 4684896
12 21284488
13 95624666
14 425523864
15 1878025074
16 8229470812
17 35836393568
18 155196577484
19 668832795812
20 2869861291134
21 12266161148622
22 52243167132940
23 221803857150698
24 938974990229088
25 3964558585350392

List of values

[1, 1, 2, 12, 66, 360, 1864, 9358, 45642, 217590, 1017626, 4684896, 21284488, 95624666, 425523864, 1878025074, 8229470812, 35836393568, 155196577484, 668832795812, 2869861291134, 12266161148622, 52243167132940, 221803857150698, 938974990229088, 3964558585350392]

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

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