A220006 - OEIS

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A220006 as a simple table

n	a(n)
1	20
2	43
3	479
4	4474
5	32959
6	204056
7	1209492
8	7316891
9	44430342
10	260942687
11	1458406289
12	7769314333
13	39698813306
14	195484409069
15	930466275825
16	4292158352171
17	19240147010037
18	84029266162705
19	358361605456031

[20,43,479,4474,32959,204056,1209492,7316891, 44430342,260942687,1458406289,7769314333, 39698813306,195484409069,930466275825, 4292158352171,19240147010037,84029266162705, 358361605456031]