A147211 - OEIS

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A147211 as a simple table

n	a(n)
1	1
2	1
3	1
4	1
5	1
6	1
7	1
8	1
9	17
10	17
11	57
12	57
13	405
14	405
15	4805
16	4805
17	131407
18	131407
19	3796773
20	3796773
21	159419173
22	159419173

[1,1,1,1,1,1,1,1,17,17,57,57,405,405,4805,4805, 131407,131407,3796773,3796773,159419173,159419173]