A327021 - cp's OEIS frontend

A327021 a(n) = (2*n-1)! / 2^(n-1) if n > 0 and a(0) = 1.

n	a(n)
0	1
1	1
2	3
3	30
4	630
5	22680
6	1247400
7	97297200
8	10216206000
9	1389404016000
10	237588086736000
11	49893498214560000
12	12623055048283680000
13	3786916514485104000000
14	1329207696584271504000000
15	539658324813214230624000000
16	250941121038144617240160000000
17	132496911908140357902804480000000

[1, 1, 3, 30, 630, 22680, 1247400, 97297200, 10216206000, 1389404016000, 237588086736000, 49893498214560000, 12623055048283680000, 3786916514485104000000, 1329207696584271504000000, 539658324813214230624000000, 250941121038144617240160000000, 132496911908140357902804480000000]

cp's OEIS Frontend

A327021 a(n) = (2*n-1)! / 2^(n-1) if n > 0 and a(0) = 1.

Table of values

List of values