Number of bond-rooted polyenoids with n edges.

Terms

a(0) =0a(1) =1a(2) =2a(3) =12a(4) =38a(5) =143a(6) =490a(7) =1768a(8) =6268a(9) =22610a(10) =81620a(11) =297160a(12) =1086172a(13) =3991995a(14) =14731290a(15) =54587280a(16) =202992808a(17) =757398510a(18) =2834493948a(19) =10637507400a(20) =40023577524a(21) =150946230006a(22) =570534370692