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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.

A352720 a(n) is the number of free polyominoes of width 2 and size n.

Table of values

n a(n)
2 1
3 1
4 4
5 5
6 12
7 18
8 37
9 60
10 117
11 200
12 379
13 669
14 1250
15 2247
16 4168
17 7570
18 13987
19 25549
20 47108
21 86319
22 158978
23 291806
24 537105
25 986786
26 1815699
27 3337560
28 6140047
29 11289571
30 20767180
31 38189927
32 70246680
33 129191148
34 237627757
35 437042337
36 803861244
37 1478488577
38 2719392160
39 5001663330
40 9199544069

List of values

[1, 1, 4, 5, 12, 18, 37, 60, 117, 200, 379, 669, 1250, 2247, 4168, 7570, 13987, 25549, 47108, 86319, 158978, 291806, 537105, 986786, 1815699, 3337560, 6140047, 11289571, 20767180, 38189927, 70246680, 129191148, 237627757, 437042337, 803861244, 1478488577, 2719392160, 5001663330, 9199544069]

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

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