# A081721 (b-file synthesized from sequence entry)
1 1
2 3
3 10
4 55
5 377
6 4291
7 60028
8 1058058
9 21552969
10 500280022
11 12969598086
12 371514016094
13 11649073935505
14 396857785692525
15 14596464294191704
16 576460770691256356
17 24330595997127372497
18 1092955780817066765469
19 52063675152021153895330
20 2621440000054016000176044