A159666 - OEIS

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A159666 as a simple table

n	a(n)
0	1
1	1
2	4
3	18
4	104
5	665
6	5430
7	45647
8	457008
9	4903380
10	58782190
11	735362309
12	10577094600
13	153445432699
14	2462688382448
15	41517435884340
16	752130797186176
17	13961847566945787
18	284698729314200574
19	5855054339061479491

[1,1,4,18,104,665,5430,45647,457008,4903380, 58782190,735362309,10577094600,153445432699, 2462688382448,41517435884340,752130797186176, 13961847566945787,284698729314200574, 5855054339061479491]