# A147833 (b-file synthesized from sequence entry) 0 1 1 0 2 0 3 12 4 12 5 60 6 252 7 636 8 2364 9 7932 10 25020 11 85116 12 280380 13 921084 14 3063996 15 10112892 16 33421884 17 110641404 18 365683644 19 1209311868 20 3999743292 21 13225194492 22 43735910076 23 144633607548 24 478279581756 25 1581644932860