A074002 - OEIS

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A074002 as a simple table

n	a(n)
1	0
2	0
3	6
4	6
5	30
6	72
7	252
8	756
9	2106
10	6642
11	19602
12	59292
13	176904
14	530712
15	1596510
16	4780782
17	14351094
18	43040160
19	129146724
20	387440172
21	1162202418

[0,0,6,6,30,72,252,756,2106,6642,19602,59292, 176904,530712,1596510,4780782,14351094,43040160, 129146724,387440172,1162202418]