# A020528 (b-file synthesized from sequence entry) 0 0 1 18 2 252 3 2520 4 22320 5 187488 6 1536192 7 12435840 8 100074240 9 802948608 10 6433016832 11 51501864960 12 412165877760 13 3297930928128 14 26385863196672 15 211096568954880 16 1688811205754880 17 13510644263682048