A243995 - OEIS

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A243995 as a simple table

n	a(n)
1	1
2	18
3	96
4	560
5	720
6	1056
7	1760
8	2000
9	3264
10	7392
11	30960
12	50800
13	172080
14	173440
15	9561600
16	13304064
17	195522560
18	1017856448
19	1026021024
20	1568010240
21	2817884160

[1,18,96,560,720,1056,1760,2000,3264,7392,30960, 50800,172080,173440,9561600,13304064,195522560, 1017856448,1026021024,1568010240,2817884160]