# A002221 (b-file synthesized from sequence entry) 1 1 2 5 3 15 4 55 5 140 6 448 7 1022 8 2710 9 6048 10 14114 11 28831 12 64091 13 123649 14 251295 15 476835 16 916972 17 1654044 18 3080159 19 5377431 20 9624588 21 16490017 22 28433473 23 47423409 24 80279375