Number of isomers of C_n H_{2n+2} O_2.

Terms

a(0) =1a(1) =2a(2) =5a(3) =11a(4) =28a(5) =69a(6) =179a(7) =463a(8) =1225a(9) =3246a(10) =8697a(11) =23366a(12) =63137a(13) =171051a(14) =465002a(15) =1266831a(16) =3459262a(17) =9462393a(18) =25926939a(19) =71139400a(20) =195451500a(21) =537608802a(22) =1480316960a(23) =4079977874a(24) =11254956840a(25) =31072771980a(26) =85850016944a(27) =237356027117a(28) =656657132953