# A066410 (b-file synthesized from sequence entry)
1 15
2 252
3 3048
4 34560
5 403200
6 4390848
7 45732192
8 487710720
9 5079674880
10 52124083200
11 542890252800
12 5618427494400
13 58517854617600
14 591272607744000
15 6026281863275520
16 60762014342184960
17 623846047297536000
18 6394202229664972800
19 64417520701204070400
20 652677739551129600000