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A163861
as a simple table
n
a(n)
0
1
1
1
2
4
3
21
4
148
5
1281
6
12942
7
150955
8
2042272
9
31912425
10
567737326
[1,1,4,21,148,1281,12942,150955,2042272,31912425, 567737326]