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A006391
as a simple table
n
a(n)
1
1
2
2
3
5
4
14
5
45
6
191
7
871
8
4682
9
27336
10
172706
11
1150322
12
7989004
[1,2,5,14,45,191,871,4682,27336,172706,1150322, 7989004]