cp's OEIS Frontend

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.

A183577 Half the number of nX2 0..3 arrays with each element equal to either the maximum or the minimum of its horizontal and vertical neighbors.

Table of values

n a(n)
1 2
2 14
3 78
4 407
5 2216
6 12024
7 65277
8 354615
9 1926386
10 10465655
11 56858572
12 308906899
13 1678265791
14 9117888439
15 49536803509
16 269129777690
17 1462162196206
18 7943819360442
19 43158185018445
20 234475238671702
21 1273886693818638

List of values

[2, 14, 78, 407, 2216, 12024, 65277, 354615, 1926386, 10465655, 56858572, 308906899, 1678265791, 9117888439, 49536803509, 269129777690, 1462162196206, 7943819360442, 43158185018445, 234475238671702, 1273886693818638]

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

Content is available under The OEIS End-User License Agreement.