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A130969
as a simple table
n
a(n)
0
1
1
1
2
2
3
4
4
9
5
20
6
51
7
128
8
345
9
944
10
2658
11
7600
12
22150
[1,1,2,4,9,20,51,128,345,944,2658,7600,22150]