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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.

A219079 Hilltop maps: number of 2Xn binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..1 2Xn array.

Table of values

n a(n)
1 1
2 11
3 47
4 165
5 625
6 2435
7 9367
8 35901
9 137865
10 529675
11 2034399
12 7813333
13 30009313
14 115260115
15 442689383
16 1700273453
17 6530386425
18 25081819099
19 96333894191
20 369997847365
21 1421082488529
22 5458073486883
23 20963291245879
24 80515511728413

List of values

[1, 11, 47, 165, 625, 2435, 9367, 35901, 137865, 529675, 2034399, 7813333, 30009313, 115260115, 442689383, 1700273453, 6530386425, 25081819099, 96333894191, 369997847365, 1421082488529, 5458073486883, 20963291245879, 80515511728413]

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

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