# A090581 (b-file synthesized from sequence entry) 1 1 2 6 3 21 4 56 5 126 6 252 7 462 8 792 9 1287 10 2001 11 2992 12 4317 13 6027 14 8162 15 10746 16 13782 17 17247 18 21087 19 25212 20 29496 21 33787 22 37917 23 41712 24 45002 25 47631 26 49467 27 50412 28 50412 29 49467 30 47631 31 45002 32 41712 33 37917 34 33787 35 29496 36 25212 37 21087 38 17247 39 13782 40 10746 41 8162 42 6027 43 4317 44 2992 45 2001 46 1287 47 792 48 462 49 252 50 126 51 56 52 21 53 6 54 1