A121392 - OEIS

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A121392 as a simple table

n	a(n)
0	1
1	1
2	2
3	5
4	15
5	55
6	252
7	1449
8	10305
9	88611
10	901204
11	10642707
12	143771206
13	2194484737
14	37458097842
15	708733666387
16	14751543118320
17	335523928599914
18	8290931998724535
19	221426442466072303
20	6362084485200488267

[1,1,2,5,15,55,252,1449,10305,88611,901204, 10642707,143771206,2194484737,37458097842, 708733666387,14751543118320,335523928599914, 8290931998724535,221426442466072303, 6362084485200488267]