# A052602 (b-file synthesized from sequence entry) 0 0 1 0 2 2 3 0 4 24 5 120 6 1440 7 15120 8 201600 9 2903040 10 47174400 11 838252800 12 16286054400 13 342486144000 14 7758867916800 15 188305108992000 16 4875010043904000 17 134094160392192000 18 3905447960494080000