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A272301
as a simple table
n
a(n)
0
1
1
1
2
2
3
4
4
9
5
23
6
66
7
204
8
664
9
2273
10
8283
11
32463
12
136434
13
605848
[1,1,2,4,9,23,66,204,664,2273,8283,32463,136434, 605848]