Search: id:A002905
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%I A002905 M2486 N0985
%S A002905 1,1,1,3,5,12,30,79,227,710,2322,8071,29503,112822,450141,1867871,
%T A002905 8037472,35787667,164551477,779945969,3804967442,19079312775,
%U A002905 98211456209,518397621443,2802993986619,15510781288250,87765472487659
%N A002905 Number of connected graphs with n edges.
%D A002905 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A002905 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002905 G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg 
               model, Phys. Rev., 164 (1967), 800-817.
%D A002905 M. L. Stein and P. R. Stein, Enumeration of Linear Graphs and Connected 
               Linear Graphs up to $p = 18$ Points. Report LA-3775, Los Alamos Scientific 
               Laboratory of the University of California, Los Alamos, NM, Oct 1967.
%H A002905 P. J. Cameron, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.html">
               Sequences realized by oligomorphic permutation groups</a>, J. Integ. 
               Seqs. Vol. 3 (2000), #00.1.5.
%H A002905 Gordon Royle, <a href="http://www.cs.uwa.edu.au/~gordon/remote/graphs/
               index.html#nums">Small graphs</a>
%H A002905 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Polynema.html">Link to a section of The World of Mathematics.</a>
%e A002905 a(3) = 3 since the three connected graphs with three edges are a path, 
               a triangle and a "Y".
%e A002905 The first difference between this sequence and A046091 is for n=9 edges 
               where we see K_{3,3}, the well-known "utility graph".
%Y A002905 Column sums of A054924 or equivalently row sums of A054923.
%Y A002905 Cf. A000664, A046091 (for connected planar graphs).
%Y A002905 Apart from a(3), same as A003089.
%Y A002905 Sequence in context: A056690 A066951 A046091 this_sequence A087610 A156436 
               A099791
%Y A002905 Adjacent sequences: A002902 A002903 A002904 this_sequence A002906 A002907 
               A002908
%K A002905 nonn,nice
%O A002905 0,4
%A A002905 N. J. A. Sloane (njas(AT)research.att.com).
%E A002905 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jan 12 2000
%E A002905 More terms from Gordon Royle (gordon(AT)maths.uwa.edu.au), Jun 05 2003
%E A002905 a(25)-a(26) from Max Alekseyev (maxale(AT)gmail.com), Sep 19 2009

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