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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.

A320553 Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most three elements and for at least one block c the smallest integer interval containing c has exactly three elements.

Table of values

n a(n)
3 2
4 5
5 12
6 29
7 66
8 145
9 315
10 676
11 1436
12 3031
13 6367
14 13323
15 27798
16 57873
17 120281
18 249657
19 517663
20 1072520
21 2220724
22 4595938
23 9508022
24 19664296
25 40659943
26 84057614
27 173750589
28 359110196
29 742150185
30 1533651213
31 3169118648
32 6548358736
33 13530454573
34 27956404705

List of values

[2, 5, 12, 29, 66, 145, 315, 676, 1436, 3031, 6367, 13323, 27798, 57873, 120281, 249657, 517663, 1072520, 2220724, 4595938, 9508022, 19664296, 40659943, 84057614, 173750589, 359110196, 742150185, 1533651213, 3169118648, 6548358736, 13530454573, 27956404705]

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

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