# A375806 (b-file synthesized from sequence entry) 0 1 1 2 2 6 3 30 4 192 5 1520 6 14220 7 153720 8 1881600 9 25728192 10 388402560 11 6415960320 12 115078138560 13 2227056923520 14 46247253212160 15 1025696098627200 16 24195406204569600 17 604862279807385600 18 15973029429800002560 19 444299711254300661760 20 12983645995613669376000