Number of graphs with n nodes, n+1 edges and no isolated vertices.

Terms

a(0) =1a(1) =5a(2) =20a(3) =73a(4) =271a(5) =974a(6) =3507a(7) =12487a(8) =44475a(9) =157814a(10) =559952a(11) =1985053a(12) =7040855a(13) =24986930a(14) =88782435a(15) =315911844a(16) =1126178655a(17) =4023135764a(18) =14406870196a(19) =51728509807a(20) =186275015554a(21) =672886200335