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A125517
as a simple table
n
a(n)
1
0
2
3
3
5
4
9
5
21
6
65
7
321
8
1383
9
7221
10
40414
11
245312
12
1552223
13
10217560
14
69410576
15
485081195
16
3473135825
[0,3,5,9,21,65,321,1383,7221,40414,245312,1552223, 10217560,69410576,485081195,3473135825]