A146009 - OEIS

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A146009 as a simple table

n	a(n)
1	1
2	1
3	1
4	1
5	3
6	9
7	22
8	75
9	380
10	2417
11	17011
12	150387
13	1725197
14	24767029
15	439881987
16	9753623996
17	269467512241
18	9272282447537
19	399403152426578
20	21537582386961680
21	1447800106086744192
22	121198502960515093107

[1,1,1,1,3,9,22,75,380,2417,17011,150387,1725197, 24767029,439881987,9753623996,269467512241, 9272282447537,399403152426578,21537582386961680, 1447800106086744192,121198502960515093107]