# A013311 (b-file synthesized from sequence entry)
1 1
2 2
3 2
4 12
5 80
6 512
7 4832
8 53872
9 654320
10 9264032
11 147228512
12 2559080832
13 48910122560
14 1017566317952
15 22822627908992
16 550081215323392
17 14178080204748800
18 388900281882678272
19 11314716065658294272