This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A129581 #7 Apr 20 2011 13:34:36
%S A129581 1,1,4,35,728,26464,1866256,251518352,66296210432,34496477587456,
%T A129581 35641657548953344,73354596197458024448,301272202649664088951808,
%U A129581 2471648811030427594714599424,40527680937730480229320939012096
%N A129581 Number of labeled prime graphs with respect to the Cartesian multiplication of graphs.
%H A129581 Ji Li, <a href="http://arXiv.org/abs/0705.0038">Prime graphs and exponential Composition of Species</a>, arXiv:0705.0038
%H A129581 Ji Li, <a href="http://dx.doi.org/10.1016/j.jcta.2008.02.008">Prime graphs and exponential composition of species</a>, J. Combin. Theory A 115 (2008) 1374-1401
%F A129581 Let D(P) be the exponential Dirichlet generating series for the species of prime graphs and let D(C) be the exponential Dirichlet generating series for the species of connected graphs. We have D(P)=log D(C)
%e A129581 Almost all connected graphs are prime graphs with respect to Cartesian product of graphs. So instead of giving an example of prime graph, we give here an example of a connected nonprime graph on vertices {1,2,3,4}:
%e A129581 1 --- 4
%e A129581 | ... |
%e A129581 2 --- 3
%e A129581 The above graph is not prime since it is the Cartesian product of two line graphs of order 2.
%Y A129581 Cf. This is the logarithmic of A001187. Unlabeled prime graphs is given by A129582.
%K A129581 easy,nonn
%O A129581 1,3
%A A129581 Ji Li (vieplivee(AT)hotmail.com), May 04 2007