# A028447 (b-file synthesized from sequence entry) 0 1 1 3 2 32 3 229 4 1845 5 14320 6 112485 7 880163 8 6895792 9 54003765 10 422983905 11 3312866080 12 25947198337 13 203223953179 14 1591695681488 15 12466511517581 16 97640484615909 17 764741896529104 18 5989627994067061 19 46912093390144139 20 367425909133064576 21 2877761124002870925