A002457 - cp's OEIS frontend

A002457 a(n) = (2n+1)!/n!^2.

n	a(n)
0	1
1	6
2	30
3	140
4	630
5	2772
6	12012
7	51480
8	218790
9	923780
10	3879876
11	16224936
12	67603900
13	280816200
14	1163381400
15	4808643120
16	19835652870
17	81676217700
18	335780006100
19	1378465288200
20	5651707681620
21	23145088600920
22	94684453367400
23	386971244197200
24	1580132580471900

[1, 6, 30, 140, 630, 2772, 12012, 51480, 218790, 923780, 3879876, 16224936, 67603900, 280816200, 1163381400, 4808643120, 19835652870, 81676217700, 335780006100, 1378465288200, 5651707681620, 23145088600920, 94684453367400, 386971244197200, 1580132580471900]

cp's OEIS Frontend

A002457 a(n) = (2n+1)!/n!^2.

Table of values

List of values