# A004386 (b-file synthesized from sequence entry) 5 1 6 48 7 1540 8 41664 9 1028790 10 24040016 11 541931236 12 11919192480 13 257575523205 14 5494563394320 15 116068178638776 16 2433440563030400 17 50718300243156000 18 1052134368066259632 19 21743950029947469800