A000891 - OEIS

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A000891 as a simple table

n	a(n)
0	1
1	3
2	20
3	175
4	1764
5	19404
6	226512
7	2760615
8	34763300
9	449141836
10	5924217936
11	79483257308
12	1081724803600
13	14901311070000
14	207426250094400
15	2913690606794775
16	41255439318353700
17	588272005095043500

[1,3,20,175,1764,19404,226512,2760615,34763300, 449141836,5924217936,79483257308,1081724803600, 14901311070000,207426250094400,2913690606794775, 41255439318353700,588272005095043500]