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A220821 as a simple table

n a(n)
1 0
2 0
3 0
4 15
5 240
6 2604
7 24180
8 207732
9 1710108
10 13739550
11 108853512
12 855732465
13 6700902804
14 52395480996
15 409733313444
16 3207687963129
17 25155951725808
18 197703130100532
19 1557413160706764
20 12298597436673711
21 97359729090421320
22 772615510913274126
23 6145842794363133324

[0,0,0,15,240,2604,24180,207732,1710108,13739550,
 108853512,855732465,6700902804,52395480996,
 409733313444,3207687963129,25155951725808,
 197703130100532,1557413160706764,
 12298597436673711,97359729090421320,
 772615510913274126,6145842794363133324]

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Last modified December 9 13:50 EST 2019. Contains 329877 sequences. (Running on oeis4.)