# A006297 (b-file synthesized from sequence entry)
2 1
3 10
4 167
5 1720
6 24164
7 256116
8 3392843
9 36703824
10 472592916
11 5188948072
12 65723863196
13 729734918432
14 9145847808784
15 102432266545800
16 1274461449989715
17 14373136466094880
18 177882700353757460
19 2017523504473479992
20 24868664942648145372