Number of monocyclic skeletons with n carbon atoms and a ring size of 5.

Terms

a(0) =1a(1) =1a(2) =4a(3) =9a(4) =28a(5) =71a(6) =198a(7) =521a(8) =1418a(9) =3773a(10) =10153a(11) =27114a(12) =72705a(13) =194531a(14) =521447a(15) =1397482a(16) =3749836a(17) =10067417a(18) =27057233a(19) =72779710a(20) =195963184a(21) =528127752a(22) =1424707167a(23) =3846943003a(24) =10397057771a(25) =28125235102a(26) =76149287981a(27) =206351312858a(28) =559642013499