A219456 - OEIS

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A219456 as a simple table

n	a(n)
1	20
2	26
3	498
4	3422
5	27967
6	197308
7	1324860
8	8405212
9	51417327
10	303703636
11	1731421125
12	9525742325
13	50654533963
14	260914306516
15	1304341448963
16	6337774514024
17	29964888604613
18	137989085373438
19	619551753355165

[20,26,498,3422,27967,197308,1324860,8405212, 51417327,303703636,1731421125,9525742325, 50654533963,260914306516,1304341448963, 6337774514024,29964888604613,137989085373438, 619551753355165]