# A267987 (b-file synthesized from sequence entry)
0 4
1 8
2 48
3 400
4 3920
5 42336
6 487872
7 5889312
8 73616400
9 945561760
10 12412647104
11 165878102208
12 2249987591488
13 30906422960000
14 429157758816000
15 6015361252737600
16 85011208292365200
17 1210159553338375200
18 17338543308064440000
19 249857534618318088000