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A003947 as a simple table

na(n)
01
15
220
380
4320
51280
65120
720480
881920
9327680
101310720
115242880
1220971520
1383886080
14335544320
151342177280
165368709120
1721474836480
1885899345920
19343597383680
201374389534720
215497558138880
2221990232555520
2387960930222080
24351843720888320

[1,5,20,80,320,1280,5120,20480,81920,327680,
 1310720,5242880,20971520,83886080,335544320,
 1342177280,5368709120,21474836480,85899345920,
 343597383680,1374389534720,5497558138880,
 21990232555520,87960930222080,351843720888320]