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A053509 as a simple table

na(n)
10
20
30
40
51
630
7735
817920
9459270
1012600000
11372027810
1211824496640
13403786706895
1414772648450560
15577227041015625
1624013333950627840
171060372471758165020
1849558656380297379840
192444960458495625410260
20127008768000000000000000

[0,0,0,0,1,30,735,17920,459270,12600000,372027810,
 11824496640,403786706895,14772648450560,
 577227041015625,24013333950627840,
 1060372471758165020,49558656380297379840,
 2444960458495625410260,127008768000000000000000]