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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.

A151647 Number of permutations of 5 indistinguishable copies of 1..n with exactly 2 adjacent element pairs in decreasing order.

Table of values

n a(n)
1 0
2 100
3 5925
4 167475
5 3882250
6 84320250
7 1791011475
8 37753995925
9 793816473600
10 16676797204500
11 350257183908625
12 7355694727665975
13 154471515733316550
14 3243914368665860350
15 68122282848892857375
16 1430568461732082827625
17 30041941039388979651100

List of values

[0, 100, 5925, 167475, 3882250, 84320250, 1791011475, 37753995925, 793816473600, 16676797204500, 350257183908625, 7355694727665975, 154471515733316550, 3243914368665860350, 68122282848892857375, 1430568461732082827625, 30041941039388979651100]

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

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