# A234854 (b-file synthesized from sequence entry) 1 1 2 4 3 18 4 96 5 624 6 4896 7 45072 8 474624 9 5619456 10 73903104 11 1069106688 12 16872800256 13 288483876864 14 5311773904896 15 104789944829952 16 2205099306123264 17 49302137885884416 18 1167150882577711104 19 29165495002777387008 20 767163772371852066816 21 21188300138891474632704