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A216834
as a simple table
n
a(n)
1
0
2
0
3
0
4
0
5
1
6
0
7
0
8
0
9
2
10
6
11
31
12
155
13
1297
14
12517
15
139854
16
1764950
17
25286953
18
404899916
[0,0,0,0,1,0,0,0,2,6,31,155,1297,12517,139854, 1764950,25286953,404899916]