# A024486 (b-file synthesized from sequence entry)
0 1
1 2
2 18
3 240
4 3850
5 68796
6 1319472
7 26604864
8 556794810
9 11993338500
10 264333180540
11 5935956324480
12 135389270500848
13 3128818447143200
14 73123195376232000
15 1725644509205633280
16 41071074678970154010
17 984853105623747983700
18 23773506148264947574500