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A181770
as a simple table
n
a(n)
0
1
1
1
2
2
3
6
4
19
5
74
6
353
7
2080
8
16023
9
159526
10
2093244
11
36265070
12
836395102
13
25794670618
[1,1,2,6,19,74,353,2080,16023,159526,2093244, 36265070,836395102,25794670618]