# A009221 (b-file synthesized from sequence entry)
0 1
1 1
2 1
3 4
4 13
5 68
6 373
7 2472
8 18649
9 152144
10 1433129
11 14034560
12 156563045
13 1799730624
14 23043285021
15 304857999232
16 4392102360241
17 65741679927552
18 1051530622359889
19 17551668357299200
20 308633929353801661