# A004390 (b-file synthesized from sequence entry) 9 1 10 80 11 3828 12 142880 13 4598126 14 134153712 15 3652745460 16 94525795200 17 2353351951665 18 56849199220528 19 1340705736329960 20 31009757554370400 21 705873715441872264 22 15855778418084805200 23 352208597900888801880