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A001426
as a simple table
n
a(n)
0
1
1
1
2
3
3
12
4
58
5
325
6
2143
7
17291
8
221805
9
11545843
10
3518930337
[1,1,3,12,58,325,2143,17291,221805,11545843, 3518930337]