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.

A122158 Smallest positive number of "triangular" shuffles of n(n+1)/2 cards needed to restore them to their original order.

Table of values

n a(n)
1 1
2 2
3 4
4 20
5 18
6 12
7 126
8 33
9 204
10 1638
11 1968
12 2010
13 504
14 17043
15 240
16 222870
17 4084080
18 12462
19 81396
20 4200
21 41790
22 24254
23 56560
24 1377090
25 30669496
26 57420
27 249480
28 93840
29 696010
30 40680
31 4627497204
32 2122260
33 4774320
34 347190
35 83800
36 103458
37 5017446420
38 1686300

List of values

[1, 2, 4, 20, 18, 12, 126, 33, 204, 1638, 1968, 2010, 504, 17043, 240, 222870, 4084080, 12462, 81396, 4200, 41790, 24254, 56560, 1377090, 30669496, 57420, 249480, 93840, 696010, 40680, 4627497204, 2122260, 4774320, 347190, 83800, 103458, 5017446420, 1686300]

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

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