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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.

A097237 Number of hierarchical orderings ("societies") of n labeled elements ("individuals") with at least two occupied levels.

Table of values

n a(n)
1 0
2 2
3 12
4 86
5 780
6 8462
7 106092
8 1507046
9 23905740
10 418581662
11 8014481772
12 166501716086
13 3728936827980
14 89530481995502
15 2293539506425452
16 62429371709206406
17 1799021068567370700
18 54707449240102350782
19 1750530594833378049132
20 58787407236482804618006

List of values

[0, 2, 12, 86, 780, 8462, 106092, 1507046, 23905740, 418581662, 8014481772, 166501716086, 3728936827980, 89530481995502, 2293539506425452, 62429371709206406, 1799021068567370700, 54707449240102350782, 1750530594833378049132, 58787407236482804618006]

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

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