# A151020 (b-file synthesized from sequence entry) 0 1 1 2 2 10 3 36 4 168 5 720 6 3304 7 15088 8 69904 9 326624 10 1535040 11 7251968 12 34448064 13 164071424 14 784830976 15 3762710272 16 18090215424 17 87167033856 18 420815500544 19 2035432822272 20 9860443239424 21 47839254740992 22 232412062604288 23 1130458029407232 24 5504894214334464 25 26834127921946624 26 130931569849067520