cp's OEIS Frontend

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.

A005173 Number of rooted trees with 3 nodes of disjoint sets of labels with union {1..n}. If a node has an empty set of labels then it must have at least two children.

Table of values

n a(n)
1 0
2 1
3 12
4 61
5 240
6 841
7 2772
8 8821
9 27480
10 84481
11 257532
12 780781
13 2358720
14 7108921
15 21392292
16 64307941
17 193185960
18 580082161
19 1741295052
20 5225982301
21 15682141200
22 47054812201
23 141181213812
24 423577195861
25 1270798696440
26 3812530307041
27 11437859356572
28 34314114940621

List of values

[0, 1, 12, 61, 240, 841, 2772, 8821, 27480, 84481, 257532, 780781, 2358720, 7108921, 21392292, 64307941, 193185960, 580082161, 1741295052, 5225982301, 15682141200, 47054812201, 141181213812, 423577195861, 1270798696440, 3812530307041, 11437859356572, 34314114940621]

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

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