A221461 - OEIS

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A221461 as a simple table

n	a(n)
1	0
2	6
3	36
4	252
5	1728
6	11880
7	81648
8	561168
9	3856896
10	26508384
11	182191680
12	1252200384
13	8606352384
14	59151316608
15	406546013952
16	2794183983360
17	19204379983872
18	131991383803392
19	907174582723584
20	6234995799161856

[0,6,36,252,1728,11880,81648,561168,3856896, 26508384,182191680,1252200384,8606352384, 59151316608,406546013952,2794183983360, 19204379983872,131991383803392,907174582723584, 6234995799161856]