Isomers of polyenes attached to benzene (see Cyvin et al. for precise definition).

Terms

a(0) =0a(1) =1a(2) =2a(3) =2a(4) =8a(5) =9a(6) =26a(7) =28a(8) =88a(9) =89a(10) =292a(11) =297a(12) =994a(13) =1001a(14) =3418a(15) =3430a(16) =11920a(17) =11934a(18) =41944a(19) =41990a(20) =149184a(21) =149221a(22) =534756a(23) =534888a(24) =1931394a(25) =1931540a(26) =7019976a(27) =7020391a(28) =25662396a(29) =25662825