# A149273 (b-file synthesized from sequence entry) 0 1 1 1 2 4 3 11 4 42 5 132 6 520 7 1761 8 6970 9 24604 10 97740 11 353886 12 1408456 13 5186830 14 20673334 15 77060191 16 307402490 17 1156225566 18 4615394884 19 17481280422 20 69812708258 21 265891539128 22 1062228300604 23 4063922007022 24 16239378774724 25 62361864245180 26 249247207795482 27 960167359575770 28 3838172631009646