# A024740 (b-file synthesized from sequence entry) 1 1 2 2 3 4 4 10 5 24 6 56 7 132 8 344 9 880 10 2216 11 5568 12 14912 13 39248 14 101952 15 265216 16 718240 17 1925376 18 5115008 19 13574976 20 37150464 21 100744448 22 271103616 23 729513984 24 2008900096 25 5495163136 26 14942424576 27 40595259392 28 112428786176 29 309465434112 30 847395311616