%I #10 Mar 02 2021 04:53:07
%S 1,1,3,12,79,1123,42065,4880753,1674021742,1612191702946,
%T 4291399235883144,31570649902282023158,644451747846907273827686,
%U 36675914469877423648734408329,5846124500387959287169919356171145
%N Number of connected switching classes of signed graphs with n nodes.
%C Also, number of unlabeled connected strength 2 Eulerian graphs with n nodes. - _Vladeta Jovovic_, Mar 14 2009
%D Bussemaker, F. C.; Cameron, P. J.; Seidel, J. J.; and Tsaranov, S. V., Tables of signed graphs, Report-WSK 91-01, Eindhoven University of Technology, Department of Mathematics and Computing Science, Eindhoven, 1991, 105 pp. MR: 92g:05001.
%H F. C. Bussemaker, P. J. Cameron, J. J. Seidel, and S. V. Tsaranov, <a href="https://www.researchgate.net/publication/241872284_Tables_of_signed_graphs ">Tables of signed graphs</a>, Report-WSK 91-01, Eindhoven University of Technology, Department of Mathematics and Computing Science, Eindhoven, 1991, 105 pp. (MR: 92g:05001).
%Y Cf. A007127, A053465.
%K nonn
%O 1,3
%A _N. J. A. Sloane_, Jul 16 2003
%E Edited by _N. J. A. Sloane_ Apr 05 2009 at the suggestion of Vladeta Jovovic