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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.

A331955 Triangle T(n,k) of number of chains of length k in partitions of an n-set ordered by refinement.

Table of values

n a(n)
0 1
1 0
2 1
3 0
4 2
5 1
6 0
7 5
8 7
9 3
10 0
11 15
12 45
13 49
14 18
15 0
16 52
17 306
18 640
19 565
20 180
21 0
22 203
23 2268
24 8176
25 13055
26 9645
27 2700
28 0
29 877
30 18425
31 108388
32 279349
33 359555
34 227745
35 56700
36 0
37 4140
38 163754
39 1523922
40 5967927
41 11918270
42 12822110
43 7095060
44 1587600

List of values

[1, 0, 1, 0, 2, 1, 0, 5, 7, 3, 0, 15, 45, 49, 18, 0, 52, 306, 640, 565, 180, 0, 203, 2268, 8176, 13055, 9645, 2700, 0, 877, 18425, 108388, 279349, 359555, 227745, 56700, 0, 4140, 163754, 1523922, 5967927, 11918270, 12822110, 7095060, 1587600]

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

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