# A123348 (b-file synthesized from sequence entry) 0 0 1 3 2 12 3 54 4 240 5 1068 6 4752 7 21144 8 94080 9 418608 10 1862592 11 8287584 12 36875520 13 164077248 14 730060032 15 3248394624 16 14453698560 17 64311583488 18 286153731072 19 1273238091264 20 5665259827200 21 25207515491328 22 112160581619712 23 499057357461504 24 2220550593085440 25 9880317087264768 26 43962369535229952