Number of bicentered hydrocarbons with n atoms.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =1a(5) =1a(6) =3a(7) =3a(8) =9a(9) =15a(10) =38a(11) =73a(12) =174a(13) =380a(14) =915a(15) =2124a(16) =5134a(17) =12281a(18) =30010a(19) =73401a(20) =181835a(21) =452165a(22) =1133252a(23) =2851710a(24) =7215262a(25) =18326528a(26) =46750268a(27) =119687146a(28) =307528889a(29) =792716193