# A052784 (b-file synthesized from sequence entry) 0 0 1 0 2 0 3 0 4 0 5 0 6 720 7 7560 8 50400 9 272160 10 1300320 11 5738040 12 23958000 13 96061680 14 373477104 15 1417295880 16 5274360000 17 19313985600 18 69770966976 19 249130574424 20 880629138000