A263541 - OEIS

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A263541 as a simple table

n	a(n)
1	1
2	2
3	4
4	6
5	40
6	43
7	705
8	789
9	1148
10	2140
11	4276
12	5512
13	6672
14	8754
15	38434
16	174501
17	493578
18	598249
19	628064
20	702774
21	1368196
22	4584004
23	13813057
24	36425906
25	87964443
26	447997476
27	1964288296

[1,2,4,6,40,43,705,789,1148,2140,4276,5512,6672, 8754,38434,174501,493578,598249,628064,702774, 1368196,4584004,13813057,36425906,87964443, 447997476,1964288296]