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A156831
as a simple table
n
a(n)
1
1
2
2
3
6
4
20
5
66
6
188
7
466
8
1022
9
2098
10
4032
11
7342
12
13090
13
22726
14
38824
15
65286
16
108902
17
179762
[1,2,6,20,66,188,466,1022,2098,4032,7342,13090, 22726,38824,65286,108902,179762]