# A214767 (b-file synthesized from sequence entry) 0 1 1 2 2 16 3 144 4 1280 5 12416 6 156288 7 2445952 8 39005696 9 569584128 10 7551139840 11 94905663488 12 1200235880448 13 15657039026176 14 204235121909760 15 2589347043356672 16 34080849916796928 17 554466780012625920 18 11679936697324273664 19 269604415927633805312 20 6025264829519275556864