# A181140 (b-file synthesized from sequence entry) 1 3 2 9 3 27 4 81 5 240 6 714 7 2124 8 6318 9 18792 10 55896 11 166260 12 494532 13 1470960 14 4375296 15 13014096 16 38709768 17 115140240 18 342478800 19 1018685808 20 3030029232 21 9012668160 22 26807724000 23 79738214400 24 237177271584 25 705471756288 26 2098389932544