A207751 - OEIS

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A207751 as a simple table

n	a(n)
1	20
2	400
3	2340
4	9450
5	51590
6	247860
7	1341606
8	6978660
9	38171520
10	206898250
11	1147824290
12	6372877952
13	35814768750
14	201958261240
15	1147016892780
16	6537970767786
17	37441623486062
18	215093421143100
19	1239764709916950

[20,400,2340,9450,51590,247860,1341606,6978660, 38171520,206898250,1147824290,6372877952, 35814768750,201958261240,1147016892780, 6537970767786,37441623486062,215093421143100, 1239764709916950]