# A002222 (b-file synthesized from sequence entry) 1 1 2 6 3 21 4 91 5 266 6 994 7 2562 8 7764 9 19482 10 51212 11 116028 12 288541 13 612463 14 1375609 15 2862437 16 6036606 17 11846488 18 24080685 19 45506290