# A002495 (b-file synthesized from sequence entry) 0 1 1 0 2 2 3 2676 4 101118 5 1644784 6 16044996 7 110148864 8 584716268 9 2549726784 10 9515920164 11 31314134428 12 92917720104 13 252775518960 14 638328487880 15 1511740834560 16 3387163064214 17 7228599229760 18 14768913424614 19 29023937463900 20 55107648867544 21 101434033397472