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A003697
as a simple table
n
a(n)
0
1
1
2
2
9
3
32
4
121
5
450
6
1681
7
6272
8
23409
9
87362
10
326041
11
1216800
12
4541161
13
16947842
[1,2,9,32,121,450,1681,6272,23409,87362,326041, 1216800,4541161,16947842]