A113247 - cp's OEIS frontend

A113247 Number of permutations pi in S_n such that maj pi and maj pi^(-1) have the same parity where maj is the major index. Equivalently, the number of pi such that maj pi and inv pi have the same parity where inv is the inversion number.

n	a(n)
0	1
1	1
2	2
3	4
4	16
5	64
6	384
7	2544
8	20352
9	181632
10	1816320
11	19960320
12	239523840
13	3113533440
14	43589468160
15	653837506560
16	10461400104960
17	177843719208960
18	3201186945761280
19	60822550297313280
20	1216451005946265600

[1, 1, 2, 4, 16, 64, 384, 2544, 20352, 181632, 1816320, 19960320, 239523840, 3113533440, 43589468160, 653837506560, 10461400104960, 177843719208960, 3201186945761280, 60822550297313280, 1216451005946265600]

cp's OEIS Frontend

A113247 Number of permutations pi in S_n such that maj pi and maj pi^(-1) have the same parity where maj is the major index. Equivalently, the number of pi such that maj pi and inv pi have the same parity where inv is the inversion number.

Table of values

List of values