A073478 - OEIS

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A073478 as a simple table

n	a(n)
0	1
1	1
2	2
3	9
4	44
5	290
6	2154
7	19026
8	186752
9	2070792
10	25119720
11	334960560
12	4824346152
13	75100568088
14	1250180063664
15	22235660291880
16	419595248663040
17	8388866239417920
18	176823515257447104
19	3923498370610292544

[1,1,2,9,44,290,2154,19026,186752,2070792, 25119720,334960560,4824346152,75100568088, 1250180063664,22235660291880,419595248663040, 8388866239417920,176823515257447104, 3923498370610292544]