A146786 - OEIS

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A146786 as a simple table

n	a(n)
1	1
2	1
3	1
4	1
5	3
6	9
7	27
8	85
9	337
10	1791
11	13253
12	115267
13	1169733
14	14374957
15	216583105
16	4102635811
17	98419728413
18	2904752917775
19	103834255604223
20	4525458320487677

[1,1,1,1,3,9,27,85,337,1791,13253,115267,1169733, 14374957,216583105,4102635811,98419728413, 2904752917775,103834255604223,4525458320487677]