# A097833 (b-file synthesized from sequence entry) 0 1 1 21 2 420 3 8380 4 167181 5 3335241 6 66537640 7 1327417560 8 26481813561 9 528308853661 10 10539695259660 11 210265596339540 12 4194772231531141 13 83685179034283281 14 1669508808454134480 15 33306490990048406320