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A271066
as a simple table
n
a(n)
0
1
1
5
2
20
3
65
4
197
5
784
6
3080
7
11980
8
46484
9
184096
10
728552
11
2897748
12
11580156
13
46293916
14
185100768
15
740296708
[1,5,20,65,197,784,3080,11980,46484,184096,728552, 2897748,11580156,46293916,185100768,740296708]