# A069053 (b-file synthesized from sequence entry)
1 1
2 4
3 36
4 144
5 3600
6 10800
7 529200
8 2116800
9 6350400
10 6350400
11 768398400
12 768398400
13 129859329600
14 129859329600
15 129859329600
16 519437318400
17 150117385017600
18 450352155052800
19 162577127974060800
20 6503085118962432