A075207 - OEIS

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A075207 as a simple table

n	a(n)
1	1
2	1
3	3
4	6
5	12
6	36
7	60
8	209
9	387
10	1054
11	1468
12	6895
13	7001
14	23920
15	49496
16	126732
17	146046
18	638800
19	647502
20	2772935
21	4162861

[1,1,3,6,12,36,60,209,387,1054,1468,6895,7001, 23920,49496,126732,146046,638800,647502,2772935, 4162861]