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A019447
as a simple table
n
a(n)
0
1
1
1
2
2
3
4
4
12
5
35
6
120
7
427
8
1628
9
6090
10
23797
11
90296
12
350726
13
1338076
14
5165957
15
19732508
[1,1,2,4,12,35,120,427,1628,6090,23797,90296, 350726,1338076,5165957,19732508]