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.

A297721 Number of 2Xn 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1, 2 or 4 neighboring 1s.

Table of values

n a(n)
1 1
2 10
3 34
4 83
5 258
6 865
7 2651
8 8041
9 25114
10 78356
11 242335
12 750668
13 2331147
14 7233125
15 22428585
16 69571574
17 215837630
18 669523807
19 2076792418
20 6442276953
21 19984194983
22 61990893369
23 192295766302
24 596503969480
25 1850361240315
26 5739832532268

List of values

[1, 10, 34, 83, 258, 865, 2651, 8041, 25114, 78356, 242335, 750668, 2331147, 7233125, 22428585, 69571574, 215837630, 669523807, 2076792418, 6442276953, 19984194983, 61990893369, 192295766302, 596503969480, 1850361240315, 5739832532268]