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A325791
as a simple table
n
a(n)
0
1
1
1
2
1
3
2
4
4
5
20
6
82
7
252
8
1074
9
7912
10
39552
11
152680
12
776094
13
5550310
14
30026848
15
108376910
[1,1,1,2,4,20,82,252,1074,7912,39552,152680, 776094,5550310,30026848,108376910]