# A024491 (b-file synthesized from sequence entry)
0 -1
1 2
2 10
3 84
4 858
5 9724
6 117572
7 1485800
8 19389690
9 259289580
10 3534526380
11 48932534040
12 686119227300
13 9723892802904
14 139067101832008
15 2004484433302736
16 29089272078453818
17 424672260824486220
18 6232570989814602524
19 91901608649243484728
20 1360850743459951600780