# A003720 (b-file synthesized from sequence entry) 0 1 1 6 2 168 3 10672 4 1198080 5 208521728 6 51874413568 7 17449541107712 8 7622674735988736 9 4193561606973095936 10 2836052065377836597248 11 2312174256451088534208512 12 2236165580390456719589769216 13 2530976708469616321520834969600 14 3314110602212685014002135203840000