A004300 - OEIS

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A004300 as a simple table

n	a(n)
1	1
2	1
3	2
4	7
5	22
6	96
7	380
8	1853
9	8510
10	44940
11	229836
12	1296410
13	7211116
14	43096912
15	256874200
16	1617413773
17	10226972110
18	67542201972
19	449809389740
20	3104409032126

[1,1,2,7,22,96,380,1853,8510,44940,229836,1296410, 7211116,43096912,256874200,1617413773,10226972110, 67542201972,449809389740,3104409032126]