A219953 - OEIS

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A219953 as a simple table

n	a(n)
1	1
2	3
3	8
4	38
5	86
6	318
7	504
8	3600
9	8132
10	83160
11	116850
12	202272
13	399126
14	6190086
15	8756916
16	25253676
17	309709400
18	1112878446
19	1478724036
20	11062089360
21	97331025386

[1,3,8,38,86,318,504,3600,8132,83160,116850, 202272,399126,6190086,8756916,25253676,309709400, 1112878446,1478724036,11062089360,97331025386]