cp's OEIS Frontend

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.

A177540 Number of permutations of {1,...,n} avoiding adjacent step pattern up, down, down, up, up, down.

Table of values

n a(n)
0 1
1 1
2 2
3 6
4 24
5 120
6 720
7 4908
8 38208
9 334368
10 3248640
11 34774112
12 405758208
13 5129918808
14 69849531936
15 1018876044528
16 15854497560576
17 262116761475488
18 4588408779868800
19 84784281517177940
20 1649073291620014880
21 33678805727832427224
22 720569710852319474016

List of values

[1, 1, 2, 6, 24, 120, 720, 4908, 38208, 334368, 3248640, 34774112, 405758208, 5129918808, 69849531936, 1018876044528, 15854497560576, 262116761475488, 4588408779868800, 84784281517177940, 1649073291620014880, 33678805727832427224, 720569710852319474016]

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

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