# A148997 (b-file synthesized from sequence entry) 0 1 1 1 2 3 3 9 4 33 5 121 6 468 7 1859 8 7558 9 31270 10 131330 11 558115 12 2396603 13 10379648 14 45292679 15 198926208 16 878692550 17 3900981744 18 17396764823 19 77896353911 20 350065380105 21 1578398595372 22 7138256186788 23 32371596240950 24 147175354377729 25 670685606484390 26 3062947647863016 27 14016157023522647