A030826 - OEIS

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A030826 as a simple table

n	a(n)
1	1
2	2
3	6
4	27
5	136
6	820
7	5742
8	45937
9	413437
10	4134377
11	45478153
12	545737843
13	7094591965
14	99324287514
15	1489864312718
16	23837829003495
17	405243093059417
18	7294375675069511
19	138593137826320724
20	2771862756526414499

[1,2,6,27,136,820,5742,45937,413437,4134377, 45478153,545737843,7094591965,99324287514, 1489864312718,23837829003495,405243093059417, 7294375675069511,138593137826320724, 2771862756526414499]