# A176475 (b-file synthesized from sequence entry) 1 0 2 1 3 2 4 8 5 24 6 136 7 960 8 5312 9 40320 10 491776 11 4112640 12 40270592 13 638668800 14 6249389056 15 91883151360 16 1919826163712 17 20922789888000 18 355897293438976 19 8676514912665600 20 121674189293944832 21 2757288942600192000