# A045630 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 9 4 32 5 125 6 450 7 1715 8 6400 9 24300 10 92250 11 352715 12 1351584 13 5200299 14 20056582 15 77558625 16 300533760 17 1166803109 18 4537542888 19 17672631899 20 68923172000 21 269128935495 22 1052049129142 23 4116715363799 24 16123800483072