Number of structurally isomeric homologs with molecular formula C_{3+n} H_{6+2n}.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =15a(5) =33a(6) =83a(7) =196a(8) =491a(9) =1214a(10) =3068a(11) =7754a(12) =19834a(13) =50872a(14) =131423a(15) =340763a(16) =887839a(17) =2321193a(18) =6090979a(19) =16031341a(20) =42319223a(21) =112003765a(22) =297164610a(23) =790190726a(24) =2105607907a(25) =5621642203a(26) =15036126167a(27) =40284850520a(28) =108102408101