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.

A228478 Number of n X 4 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically or antidiagonally.

Table of values

n a(n)
1 3
2 9
3 41
4 172
5 728
6 3084
7 13050
8 55252
9 233875
10 990055
11 4191028
12 17741339
13 75101906
14 317918500
15 1345800258
16 5696989354
17 24116274286
18 102088075950
19 432155280235
20 1829382955772
21 7744072911728
22 32781908823977
23 138771103836595

List of values

[3, 9, 41, 172, 728, 3084, 13050, 55252, 233875, 990055, 4191028, 17741339, 75101906, 317918500, 1345800258, 5696989354, 24116274286, 102088075950, 432155280235, 1829382955772, 7744072911728, 32781908823977, 138771103836595]

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

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