0,4

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.

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.

P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

Gordon Royle, Small graphs

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

a(3) = 3 since the three connected graphs with three edges are a path, a triangle and a "Y".

The first difference between this sequence and A046091 is for n=9 edges where we see K_{3,3}, the well-known "utility graph".

Column sums of A054924 or equivalently row sums of A054923.

Cf. A000664, A046091 (for connected planar graphs).

Apart from a(3), same as A003089.

Sequence in context: A056690 A066951 A046091 this_sequence A087610 A156436 A099791

Adjacent sequences: A002902 A002903 A002904 this_sequence A002906 A002907 A002908

nonn,nice

N. J. A. Sloane (njas(AT)research.att.com).

More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jan 12 2000

More terms from Gordon Royle (gordon(AT)maths.uwa.edu.au), Jun 05 2003

a(25)-a(26) from Max Alekseyev (maxale(AT)gmail.com), Sep 19 2009