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.

A007868 Number of inverse pairs of elements in symmetric group S_n, or pairs of total orders on n nodes (average of A000085 and A000142).

Table of values

n a(n)
0 1
1 1
2 2
3 5
4 17
5 73
6 398
7 2636
8 20542
9 182750
10 1819148
11 19976248
12 239570876
13 3113794652
14 43590340840
15 653842358768
16 10461418047368
17 177843819947656
18 3201187351520912
19 60822552609266720
20 1216451015967652048
21 25545471145831066448
22 562000364198246159456

List of values

[1, 1, 2, 5, 17, 73, 398, 2636, 20542, 182750, 1819148, 19976248, 239570876, 3113794652, 43590340840, 653842358768, 10461418047368, 177843819947656, 3201187351520912, 60822552609266720, 1216451015967652048, 25545471145831066448, 562000364198246159456]

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

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