# A004346 (b-file synthesized from sequence entry)
4 1
5 25
6 435
7 6545
8 91390
9 1221759
10 15890700
11 202927725
12 2558620845
13 31966749880
14 396704524216
15 4898229264825
16 60246643120300
17 738799683460650
18 9038619861406740
19 110375347398090219
20 1345860629046814650