Number of graphs with n nodes and n-1 edges.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =6a(5) =15a(6) =41a(7) =115a(8) =345a(9) =1103a(10) =3664a(11) =12763a(12) =46415a(13) =175652a(14) =691001a(15) =2821116a(16) =11932174a(17) =52211412a(18) =236007973a(19) =1100528508a(20) =5287050500a(21) =26134330813a(22) =132760735671a(23) =692294900849