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A280763
as a simple table
n
a(n)
1
1
2
1
3
2
4
6
5
18
6
75
7
318
8
1599
9
8439
10
48824
11
300747
12
2030086
13
15425065
14
141798617
[1,1,2,6,18,75,318,1599,8439,48824,300747,2030086, 15425065,141798617]