A000680 - cp's OEIS frontend

A000680 a(n) = (2n)!/2^n.

n	a(n)
0	1
1	1
2	6
3	90
4	2520
5	113400
6	7484400
7	681080400
8	81729648000
9	12504636144000
10	2375880867360000
11	548828480360160000
12	151476660579404160000
13	49229914688306352000000
14	18608907752179801056000000
15	8094874872198213459360000000
16	4015057936610313875842560000000

[1, 1, 6, 90, 2520, 113400, 7484400, 681080400, 81729648000, 12504636144000, 2375880867360000, 548828480360160000, 151476660579404160000, 49229914688306352000000, 18608907752179801056000000, 8094874872198213459360000000, 4015057936610313875842560000000]

cp's OEIS Frontend

A000680 a(n) = (2n)!/2^n.

Table of values

List of values