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A197899
as a simple table
n
a(n)
1
1
2
4
3
12
4
131
5
2261
6
68915
7
3936847
8
398896240
9
73105887206
10
24124756465130
[1,4,12,131,2261,68915,3936847,398896240, 73105887206,24124756465130]