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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.

A134955 Number of "hyperforests" on n unlabeled nodes, i.e., hypergraphs that have no cycles, assuming that each edge contains at least two vertices.

Table of values

n a(n)
0 1
1 1
2 2
3 4
4 9
5 20
6 50
7 128
8 351
9 1009
10 3035
11 9464
12 30479
13 100712
14 340072
15 1169296
16 4082243
17 14438577
18 51643698
19 186530851
20 679530937
21 2494433346
22 9219028889
23 34280914106
24 128179985474
25 481694091291
26 1818516190252
27 6894350122452

List of values

[1, 1, 2, 4, 9, 20, 50, 128, 351, 1009, 3035, 9464, 30479, 100712, 340072, 1169296, 4082243, 14438577, 51643698, 186530851, 679530937, 2494433346, 9219028889, 34280914106, 128179985474, 481694091291, 1818516190252, 6894350122452]

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

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