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.

A169637 The number of permutations of the first n elements of the Hofstaedter Q-sequence (A005185), augmented by Q(0)=1.

Table of values

n a(n)
0 1
1 1
2 1
3 4
4 20
5 60
6 420
7 3360
8 15120
9 151200
10 831600
11 3326400
12 43243200
13 302702400
14 1513512000
15 24216192000
16 411675264000
17 3705077376000
18 70396470144000
19 703964701440000
20 14783258730240000
21 162615846032640000
22 1246721486250240000
23 7480328917501440000

List of values

[1, 1, 1, 4, 20, 60, 420, 3360, 15120, 151200, 831600, 3326400, 43243200, 302702400, 1513512000, 24216192000, 411675264000, 3705077376000, 70396470144000, 703964701440000, 14783258730240000, 162615846032640000, 1246721486250240000, 7480328917501440000]

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

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