# A001757 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 9
4 54
5 450
6 4500
7 55125
8 771750
9 12502350
10 225042300
11 4538353050
12 99843767100
13 2410513805700
14 62673358948200
15 1762688220418125
16 52880646612543750
17 1698056319002793750
18 57733914846094987500
19 2084194325944029048750