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A197156
as a simple table
n
a(n)
1
1
2
3
3
5
4
20
5
56
6
225
7
819
8
3333
9
13336
10
55231
11
229146
12
963284
13
4068503
14
17301000
15
73893082
[1,3,5,20,56,225,819,3333,13336,55231,229146, 963284,4068503,17301000,73893082]