Number of connected graphs with n nodes, n+2 edges.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =4a(5) =22a(6) =107a(7) =486a(8) =2075a(9) =8548a(10) =33851a(11) =130365a(12) =489387a(13) =1799700a(14) =6499706a(15) =23118465a(16) =81134475a(17) =281454170a(18) =966388692a(19) =3288208176a(20) =11098235911a(21) =37188198356a(22) =123800999503a(23) =409715126169