%I A003089 M1417
%S A003089 1,1,2,5,12,30,79,227,710,2322,8071,29503,112822,450141,1867871,8037472,
%T A003089 35787667,164551477,779945969,3804967442,19079312775,98211456209,
%U A003089 518397621443,2802993986619
%N A003089 Number of connected line graphs with n nodes.
%C A003089 Sequence is identical to the number of connected graphs on n edges (A002905), 
               except for the term a(3). The three connected 3-edge graphs (P_4, 
               K_3 and K_{1,3}) yield only two linegraphs because K_3 and K_{1,3} 
               have isomorphic linegraphs. No other connected nonisomorphic graphs 
               have isomorphic linegraphs.
%D A003089 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 
               1973, p. 221.
%D A003089 R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
%D A003089 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%Y A003089 Cf. A002905.
%Y A003089 Sequence in context: A136704 A120895 A101785 this_sequence A112412 A125023 
               A129804
%Y A003089 Adjacent sequences: A003086 A003087 A003088 this_sequence A003090 A003091 
               A003092
%K A003089 nonn,nice
%O A003089 1,3
%A A003089 N. J. A. Sloane (njas(AT)research.att.com).
%E A003089 More terms from R. C. Read (rcread(AT)math.uwaterloo.ca).
%E A003089 More terms from Gordon Royle (gordon(AT)maths.uwa.edu.au), Jun 05 2003