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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.

A271789 Number of set partitions of [n] having exactly two pairs (m,m+1) such that m is in some block b and m+1 is in block b+1.

Table of values

n a(n)
2 0
3 1
4 6
5 24
6 86
7 307
8 1143
9 4513
10 18956
11 84546
12 399218
13 1989792
14 10439521
15 57504306
16 331747730
17 1999924893
18 12571830681
19 82245682149
20 558951842996
21 3939679356783
22 28754596249395
23 217019729585609
24 1691485555633721
25 13598390501982510
26 112633410446366669

List of values

[0, 1, 6, 24, 86, 307, 1143, 4513, 18956, 84546, 399218, 1989792, 10439521, 57504306, 331747730, 1999924893, 12571830681, 82245682149, 558951842996, 3939679356783, 28754596249395, 217019729585609, 1691485555633721, 13598390501982510, 112633410446366669]

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

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