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A000017
as a simple table
n
a(n)
1
1
2
0
3
0
4
2
5
2
6
4
7
8
8
4
9
16
10
12
11
48
12
80
13
136
14
420
15
1240
16
2872
17
7652
18
18104
19
50184
[1,0,0,2,2,4,8,4,16,12,48,80,136,420,1240,2872, 7652,18104,50184]