A204424 - OEIS

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A204424 as a simple table

n	a(n)
1	0
2	2
3	9
4	16
5	144
6	1032
7	5184
8	48816
9	530712
10	4188672
11	50015232
12	707802624
13	7614259200
14	112586112000
15	1938416832000
16	26579819520000
17	469224244224000
18	9509523337728000
19	158654296829952000
20	3261008730405888000

[0,2,9,16,144,1032,5184,48816,530712,4188672, 50015232,707802624,7614259200,112586112000, 1938416832000,26579819520000,469224244224000, 9509523337728000,158654296829952000, 3261008730405888000]