Number of n-node connected graphs with at most one cycle.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =8a(6) =19a(7) =44a(8) =112a(9) =287a(10) =763a(11) =2041a(12) =5577a(13) =15300a(14) =42419a(15) =118122a(16) =330785a(17) =929469a(18) =2621272a(19) =7411706a(20) =21010378a(21) =59682057a(22) =169859257a(23) =484234165a(24) =1382567947a(25) =3952860475a(26) =11315775161a(27) =32430737380a(28) =93044797486a(29) =267211342954