# A018075 (b-file synthesized from sequence entry) 0 1 1 1 2 3 3 6 4 11 5 20 6 36 7 66 8 121 9 220 10 401 11 730 12 1331 13 2423 14 4414 15 8039 16 14641 17 26663 18 48558 19 88433 20 161051 21 293299 22 534145 23 972765 24 1771561 25 3226296 26 5875603 27 10700415 28 19487171 29 35489261 30 64631634 31 117704565