Number of connected graphs with n nodes and n+1 edges.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =19a(6) =67a(7) =236a(8) =797a(9) =2678a(10) =8833a(11) =28908a(12) =93569a(13) =300748a(14) =959374a(15) =3042808a(16) =9597679a(17) =30134509a(18) =94218306a(19) =293509092a(20) =911325798a(21) =2821327949a(22) =8711297753a(23) =26833501800a(24) =82476837698a(25) =253007383067a(26) =774737986836