A026575 - OEIS

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A026575 as a simple table

n	a(n)
1	1
2	2
3	12
4	38
5	200
6	701
7	3682
8	13294
9	70665
10	258430
11	1388002
12	5114572
13	27682135
14	102539204
15	558172494
16	2075658454
17	11348521989
18	42330184638

[1,2,12,38,200,701,3682,13294,70665,258430, 1388002,5114572,27682135,102539204,558172494, 2075658454,11348521989,42330184638]