# A006781 (b-file synthesized from sequence entry)
1 1
2 2
3 7
4 32
5 168
6 970
7 5984
8 38786
9 261160
10 1812630
11 12895360
12 93638634
13 691793872
14 5186869122
15 39388514522
16 302457399674
17 2345362579172
18 18345337742960
19 144612959167806
20 1147920496989270
21 9169516892088470