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A217728
as a simple table
n
a(n)
1
1
2
1
3
2
4
8
5
304
6
2160640
7
4256950094225408
8
117462917657284681348398871061442068480
[1,1,2,8,304,2160640,4256950094225408, 117462917657284681348398871061442068480]