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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.

A217995 Number of n X 1 arrays of the minimum or maximum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 1 array.

Table of values

n a(n)
1 3
2 9
3 25
4 81
5 241
6 719
7 2181
8 6543
9 19623
10 58983
11 176995
12 531045
13 1593739
14 4781741
15 14346105
16 43041933
17 129130449
18 387399819
19 1162223437
20 3486708387
21 10460197183
22 31380761819
23 94142587347
24 282428344593
25 847286292987
26 2541861239481

List of values

[3, 9, 25, 81, 241, 719, 2181, 6543, 19623, 58983, 176995, 531045, 1593739, 4781741, 14346105, 43041933, 129130449, 387399819, 1162223437, 3486708387, 10460197183, 31380761819, 94142587347, 282428344593, 847286292987, 2541861239481]

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

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