# A018109 (b-file synthesized from sequence entry) 0 1 1 2 2 5 3 10 4 22 5 48 6 103 7 223 8 484 9 1048 10 2270 11 4917 12 10648 13 23061 14 49944 15 108165 16 234256 17 507337 18 1098758 19 2379621 20 5153632 21 11161410 22 24172677 23 52351655 24 113379904 25 245551027 26 531798889 27 1151736408