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A220817 as a simple table

n a(n)
1 4
2 10
3 40
4 215
5 1260
6 8010
7 53240
8 366680
9 2590420
10 18674660
11 136809240
12 1015603015
13 7622900360
14 57753364510
15 441081947840
16 3392237023425
17 26248421645200
18 204202630151860
19 1596256637347240
20 12531697773337965
21 98763817012822460
22 781102051887068160

[4,10,40,215,1260,8010,53240,366680,2590420,
 18674660,136809240,1015603015,7622900360,
 57753364510,441081947840,3392237023425,
 26248421645200,204202630151860,1596256637347240,
 12531697773337965,98763817012822460,
 781102051887068160]

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Last modified December 14 22:42 EST 2019. Contains 329987 sequences. (Running on oeis4.)