# A056197 (b-file synthesized from sequence entry) 0 1 1 7 2 38 3 222 4 1464 5 10920 6 91440 7 851760 8 8749440 9 98340480 10 1201132800 11 15846969600 12 224651750400 13 3406180377600 14 55009501747200 15 942833219328000 16 17093919338496000 17 326876746420224000 18 6575237795782656000