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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.

A305839 Number of unlabeled forests of rooted trees with 2n edges and n connected components, in which the outdegree of each node is <= 2 and the symmetric group acts on the components.

Table of values

n a(n)
0 1
1 1
2 3
3 6
4 15
5 32
6 77
7 172
8 405
9 930
10 2180
11 5070
12 11914
13 27929
14 65829
15 155202
16 367053
17 868990
18 2061723
19 4897502
20 11652547
21 27757960
22 66210042
23 158103242
24 377957299
25 904439542
26 2166408422
27 5193894809
28 12463003846
29 29929966312
30 71933014935
31 173009938416

List of values

[1, 1, 3, 6, 15, 32, 77, 172, 405, 930, 2180, 5070, 11914, 27929, 65829, 155202, 367053, 868990, 2061723, 4897502, 11652547, 27757960, 66210042, 158103242, 377957299, 904439542, 2166408422, 5193894809, 12463003846, 29929966312, 71933014935, 173009938416]

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

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