A146580 - OEIS

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A146580 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	457
14	457
15	7575
16	7575
17	206575
18	206575
19	7284891
20	7284891
21	429058537
22	429058537
23	43146239725
24	43146239725

[1,1,1,1,1,1,1,1,17,17,57,57,457,457,7575,7575, 206575,206575,7284891,7284891,429058537,429058537, 43146239725,43146239725]