# A027121 (b-file synthesized from sequence entry) 2 1 3 4 4 13 5 40 6 120 7 352 8 1022 9 2948 10 8473 11 24304 12 69649 13 199544 14 571795 15 1639244 16 4702499 17 13500396 18 38790727 19 111555296 20 321100627 21 925086012 22 2667533646 23 7698716068 24 22238169212 25 64289860528 26 186010834243 27 538611262492