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A215873
as a simple table
n
a(n)
1
1
2
1
3
1
4
4
5
20
6
189
7
1642
8
26451
9
307874
10
7027942
11
98057806
12
2850280812
13
44974137856
[1,1,1,4,20,189,1642,26451,307874,7027942, 98057806,2850280812,44974137856]