A215074 - OEIS

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A215074 as a simple table

n	a(n)
1	1
2	1
3	2
4	4
5	12
6	40
7	154
8	660
9	3113
10	15893
11	86857
12	502092
13	3036032
14	19006591
15	122119857
16	799665333
17	5308126648
18	35576413852
19	240063646519
20	1627605038848

[1,1,2,4,12,40,154,660,3113,15893,86857,502092, 3036032,19006591,122119857,799665333,5308126648, 35576413852,240063646519,1627605038848]