# A150072 (b-file synthesized from sequence entry) 0 1 1 2 2 6 3 18 4 65 5 235 6 924 7 3584 8 14685 9 59739 10 252404 11 1057050 12 4552029 13 19472054 14 85142974 15 369881012 16 1635207275 17 7189370970 18 32073487208 19 142355800384 20 639620083601 21 2860850548252 22 12931842528134 23 58210175585589 24 264437645539445 25 1196711869085656 26 5459851377934327 27 24821711727873379