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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.

A228408 Number of permutations of [n] with exactly two (possibly overlapping) occurrences of some of the consecutive step patterns UUD, UDU, DUU (U=up, D=down).

Table of values

n a(n)
0 0
1 0
2 0
3 0
4 0
5 29
6 230
7 1537
8 11208
9 89657
10 724755
11 6010150
12 55305521
13 545054759
14 5504044595
15 59482056555
16 690974195737
17 8306302563795
18 104653460921783
19 1401318441726295
20 19525683104731681
21 282626170020405627
22 4296152288224050974
23 67974610534037861728

List of values

[0, 0, 0, 0, 0, 29, 230, 1537, 11208, 89657, 724755, 6010150, 55305521, 545054759, 5504044595, 59482056555, 690974195737, 8306302563795, 104653460921783, 1401318441726295, 19525683104731681, 282626170020405627, 4296152288224050974, 67974610534037861728]

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

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