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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.

A272064 Number of set partitions of [n] such that for each pair of consecutive blocks (b,b+1) exactly one pair of consecutive numbers (i,i+1) exists with i member of b and i+1 member of b+1.

Table of values

n a(n)
0 1
1 1
2 2
3 5
4 13
5 35
6 102
7 332
8 1205
9 4796
10 20640
11 95197
12 467694
13 2435804
14 13394117
15 77490260
16 470198899
17 2984034004
18 19757370537
19 136171758636
20 975002124101
21 7239322944625
22 55648169854405
23 442195755123607
24 3627392029179270
25 30679238282421267
26 267215329668444337

List of values

[1, 1, 2, 5, 13, 35, 102, 332, 1205, 4796, 20640, 95197, 467694, 2435804, 13394117, 77490260, 470198899, 2984034004, 19757370537, 136171758636, 975002124101, 7239322944625, 55648169854405, 442195755123607, 3627392029179270, 30679238282421267, 267215329668444337]

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

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