# A067680 (b-file synthesized from sequence entry)
1 6
2 21
3 54
4 75
5 441
6 1071
7 4191
8 9315
9 58311
10 4197375
11 7685151
12 36997695
13 268460031
14 1073790975
15 17180065791
16 13517087570210304
17 18014398710808575
18 288230376957018111