# A003228 (b-file synthesized from sequence entry) 1 1 2 2 3 2 4 5 5 9 6 21 7 43 8 101 9 226 10 556 11 1333 12 3365 13 8500 14 22007 15 57258 16 151264 17 401761 18 1077063 19 2902599 20 7871250 21 21440642 22 58672589 23 161155637 24 444240627 25 1228400744 26 3406668865 27 9472308269 28 26402207803 29 73755064178