Number of n-node connected unicyclic graphs.

Terms

a(0) =1a(1) =2a(2) =5a(3) =13a(4) =33a(5) =89a(6) =240a(7) =657a(8) =1806a(9) =5026a(10) =13999a(11) =39260a(12) =110381a(13) =311465a(14) =880840a(15) =2497405a(16) =7093751a(17) =20187313a(18) =57537552a(19) =164235501a(20) =469406091a(21) =1343268050a(22) =3848223585a(23) =11035981711a(24) =31679671920a(25) =91021354454a(26) =261741776369a(27) =753265624291