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A180840
as a simple table
n
a(n)
1
1
2
0
3
2
4
17
5
131
6
1220
7
13796
8
183095
9
2790353
10
48045596
11
922507880
12
19543670381
13
452869998215
[1,0,2,17,131,1220,13796,183095,2790353,48045596, 922507880,19543670381,452869998215]