# A013227 (b-file synthesized from sequence entry) 0 0 1 0 2 -1 3 1 4 -6 5 15 6 -135 7 600 8 -6580 9 42805 10 -546525 11 4698450 12 -68473350 13 732163575 14 -12012875875 15 153571600000 16 -2805371985000 17 41710773599625 18 -840435196901625 19 14241298404498750 20 -313987574315496250