A127021 - OEIS

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A127021 as a simple table

n	a(n)
4	1
5	11
6	80
7	491
8	2777
9	15120
10	81371
11	440947
12	2441334
13	13976885
14	83547881
15	525082654
16	3483272777
17	24413200487
18	180517606216
19	1404147099951
20	11449330342717
21	97521479081952
22	864955731435983
23	7966538662094103

[1,11,80,491,2777,15120,81371,440947,2441334, 13976885,83547881,525082654,3483272777, 24413200487,180517606216,1404147099951, 11449330342717,97521479081952,864955731435983, 7966538662094103]