A000140 - cp's OEIS frontend

A000140 Kendall-Mann numbers: the most common number of inversions in a permutation on n letters is floor(n*(n-1)/4); a(n) is the number of permutations with this many inversions.

n	a(n)
1	1
2	1
3	2
4	6
5	22
6	101
7	573
8	3836
9	29228
10	250749
11	2409581
12	25598186
13	296643390
14	3727542188
15	50626553988
16	738680521142
17	11501573822788
18	190418421447330
19	3344822488498265
20	62119523114983224
21	1214967840930909302
22	24965661442811799655
23	538134522243713149122

[1, 1, 2, 6, 22, 101, 573, 3836, 29228, 250749, 2409581, 25598186, 296643390, 3727542188, 50626553988, 738680521142, 11501573822788, 190418421447330, 3344822488498265, 62119523114983224, 1214967840930909302, 24965661442811799655, 538134522243713149122]

cp's OEIS Frontend

A000140 Kendall-Mann numbers: the most common number of inversions in a permutation on n letters is floor(n*(n-1)/4); a(n) is the number of permutations with this many inversions.

Table of values

List of values