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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.

A139415 Number of preferential arrangements (or hierarchical orderings) on the disconnected graphs on n unlabeled nodes.

Table of values

n a(n)
0 0
1 0
2 2
3 8
4 40
5 208
6 1408
7 12224
8 157312
9 3478528
10 147761664
11 12592434176
12 2112188653568
13 680441850810368
14 415073848421801984
15 476853486273606582272
16 1030736815796444156755968
17 4196432048875514376435007488
18 32243698461915435195120257335296

List of values

[0, 0, 2, 8, 40, 208, 1408, 12224, 157312, 3478528, 147761664, 12592434176, 2112188653568, 680441850810368, 415073848421801984, 476853486273606582272, 1030736815796444156755968, 4196432048875514376435007488, 32243698461915435195120257335296]

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

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