# A018087 (b-file synthesized from sequence entry) 0 1 1 1 2 3 3 7 4 15 5 29 6 58 7 114 8 225 9 442 10 871 11 1714 12 3375 13 6641 14 13071 15 25724 16 50625 17 99629 18 196069 19 385863 20 759375 21 1494442 22 2941046 23 5787949 24 11390625 25 22416632 26 44115700 27 86819243 28 170859375