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A121188
as a simple table
n
a(n)
1
1
2
1
3
1
4
3
5
6
6
18
7
44
8
129
9
354
10
1040
11
2961
12
8662
13
25022
14
73005
15
211723
16
616522
17
1789320
18
5203258
19
15097067
[1,1,1,3,6,18,44,129,354,1040,2961,8662,25022, 73005,211723,616522,1789320,5203258,15097067]