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A057724
as a simple table
n
a(n)
1
1
2
3
3
9
4
42
5
180
6
889
7
4392
8
22432
9
115469
10
602112
11
3161949
12
16723643
13
88933764
14
475286752
15
2550780323
[1,3,9,42,180,889,4392,22432,115469,602112, 3161949,16723643,88933764,475286752,2550780323]