# A006658 (b-file synthesized from sequence entry)
3 5
4 56
5 580
6 5894
7 60312
8 624240
9 6540510
10 69323910
11 742518832
12 8028001566
13 87526544560
14 961412790002
15 10630964761766
16 118257400015312
17 1322564193698320
18 14863191405246888
19 167771227744292160
20 1901345329566422790