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A218957
as a simple table
n
a(n)
0
1
1
1
2
1
3
4
4
11
5
51
6
241
7
1506
8
9649
9
80281
10
640741
11
6196576
12
66883411
13
775421219
[1,1,1,4,11,51,241,1506,9649,80281,640741,6196576, 66883411,775421219]