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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.

A276720 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements.

Table of values

n a(n)
0 1
1 1
2 2
3 5
4 15
5 37
6 87
7 208
8 515
9 1271
10 3112
11 7594
12 18578
13 45510
14 111464
15 272839
16 667809
17 1634784
18 4002217
19 9797781
20 23985131
21 58715973
22 143739040
23 351879841
24 861416293
25 2108779100
26 5162371032
27 12637686756
28 30937555540
29 75736343956
30 185405513889
31 453879917561

List of values

[1, 1, 2, 5, 15, 37, 87, 208, 515, 1271, 3112, 7594, 18578, 45510, 111464, 272839, 667809, 1634784, 4002217, 9797781, 23985131, 58715973, 143739040, 351879841, 861416293, 2108779100, 5162371032, 12637686756, 30937555540, 75736343956, 185405513889, 453879917561]

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

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