A142990 - OEIS

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A142990 as a simple table

n	a(n)
1	1
2	7
3	57
4	504
5	4896
6	51912
7	598392
8	7459200
9	100085760
10	1439061120
11	22083719040
12	360371773440
13	6232667212800
14	113901166310400
15	2193425619840000
16	44398776748032000
17	942498015750144000
18	20938290999865344000

[1,7,57,504,4896,51912,598392,7459200,100085760, 1439061120,22083719040,360371773440,6232667212800, 113901166310400,2193425619840000, 44398776748032000,942498015750144000, 20938290999865344000]