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A121184
as a simple table
n
a(n)
1
0
2
0
3
1
4
4
5
16
6
50
7
160
8
476
9
1431
10
4203
11
12369
12
36129
13
105451
14
307179
15
893495
16
2598476
17
7545168
[0,0,1,4,16,50,160,476,1431,4203,12369,36129, 105451,307179,893495,2598476,7545168]