# A007334 (b-file synthesized from sequence entry)
2 1
3 2
4 8
5 50
6 432
7 4802
8 65536
9 1062882
10 20000000
11 428717762
12 10319560704
13 275716983698
14 8099130339328
15 259492675781250
16 9007199254740992
17 336755653118801858
18 13493281232954916864
19 576882827135242335362
20 26214400000000000000000