# A153197 (b-file synthesized from sequence entry) 0 1 1 2 2 5 3 15 4 51 5 189 6 748 7 3128 8 13731 9 62969 10 300552 11 1488704 12 7634723 13 40464741 14 221311617 15 1247444859 16 7238458309 17 43196661875 18 264878725516 19 1667564565616 20 10770316016557 21 71314258947903 22 483765644021787 23 3359905164274725