# A009721 (b-file synthesized from sequence entry)
0 0
1 1
2 2
3 3
4 20
5 157
6 902
7 6895
8 77352
9 837145
10 9239882
11 124480059
12 1864519868
13 28461793141
14 470175087566
15 8596601614567
16 165789417707088
17 3347308657310641
18 72262366126097810
19 1655981959056540147
20 39676337445225379172
21 996780437366905850317