A030858 - OEIS

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A030858 as a simple table

n	a(n)
1	1
2	2
3	6
4	27
5	139
6	836
7	5855
8	46845
9	421606
10	4216064
11	46376705
12	556520461
13	7234765995
14	101286723938
15	1519300859080
16	24308813745287
17	413249833669886
18	7438497006057962
19	141331443115101290
20	2826628862302025808

[1,2,6,27,139,836,5855,46845,421606,4216064, 46376705,556520461,7234765995,101286723938, 1519300859080,24308813745287,413249833669886, 7438497006057962,141331443115101290, 2826628862302025808]