A120566 - OEIS

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A120566 as a simple table

n	a(n)
1	1
2	1
3	1
4	3
5	7
6	33
7	109
8	643
9	2623
10	17929
11	85349
12	652395
13	3517911
14	29484193
15	176844781
16	1605009651
17	10575269935
18	103033059513
19	738834271605
20	7676696689275
21	59466011617671
22	655467253898577
23	5451048833933693

[1,1,1,3,7,33,109,643,2623,17929,85349,652395, 3517911,29484193,176844781,1605009651,10575269935, 103033059513,738834271605,7676696689275, 59466011617671,655467253898577,5451048833933693]