# A009624 (b-file synthesized from sequence entry) 0 0 1 1 2 2 3 4 4 16 5 56 6 288 7 1576 8 9920 9 70912 10 541184 11 4668544 12 42274816 13 423673472 14 4449451776 15 50674728448 16 605255720960 17 7717401038848 18 103187353223168 19 1456461190426624 20 21528004660707328 21 333308651379949568