# A006801 (b-file synthesized from sequence entry) 1 1 2 2 3 5 4 13 5 34 6 90 7 239 8 635 9 1689 10 4494 11 11960 12 31832 13 84727 14 225524 15 600302 16 1597904 17 4253371 18 11321838 19 30137079 20 80220557 21 213535632 22 568401380 23 1513003529