# A036724 (b-file synthesized from sequence entry) 0 1 1 1 2 3 3 18 4 109 5 768 6 5652 7 43618 8 346353 9 2816526 10 23321925 11 196005552 12 1667527836 13 14333190427 14 124283998707 15 1085847441828 16 9549523972105 17 84471264138366 18 751042470499425 19 6708237169875867 20 60164133936171522