Number of esters with n carbon atoms up to structural isomerism.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =20a(5) =45a(6) =105a(7) =249a(8) =599a(9) =1463a(10) =3614a(11) =9016a(12) =22695a(13) =57564a(14) =146985a(15) =377555a(16) =974924a(17) =2529308a(18) =6589734a(19) =17234114a(20) =45228343a(21) =119069228a(22) =314368027a(23) =832193902a(24) =2208347917a(25) =5873364623a(26) =15653499416a(27) =41800070483a(28) =111821751649