# A081891 (b-file synthesized from sequence entry) 0 1 1 4 2 14 3 64 4 830 5 14704 6 228734 7 3136144 8 39450110 9 468241264 10 5338397054 11 59140070224 12 641540046590 13 6850671429424 14 72282030453374 15 755587489260304 16 7840735233590270 17 80889167950995184 18 830567232465613694 19 8495462278285810384 20 86620589245358801150 21 880864903819470714544