%I #10 Jul 14 2018 07:43:22
%S 1,1,2,2,2,3,3,4,3,7,4,5,7,6,5,8,5,10,9,8,6,14,8,10,9,13,8,19,8,12,13,
%T 13,13,19,10,14,15,20,11,25,11,19,19,17,12,26,14,22,19,22,14,26,19,26,
%U 21,22,15,40,16,23,25,24,23,37,17,28,25,37,18,38,19,28,31,31,25,43,20
%N Number of non-isomorphic connected I-graphs I(n,j,k) on 2n vertices (1<=j,k<=Floor[(n-1)/2]).
%C The I-graph I(n,j,k) is a graph with vertex set V(I(n,j,k)) = {u_0,u_1,...,u_{n-1},v_0,v_1,...,v_{n-1}} and edge set E(I(n,j,k)) = {u_i u_{i+j}, u_i v_i, v_i v_{i+k} : i=0,...,n-1}, where the subscripts are to be read modulo n. The I-graphs generalize the family of generalized Petersen graphs.
%D I. Z. Bouwer, W. W. Chernoff, B. Monson and Z. Star, The Foster Census (Charles Babbage Research Centre, 1988), ISBN 0-919611-19-2.
%H Marko Boben, Tomaz Pisanski, Arjana Zitnik, <a href="https://doi.org/10.1002/jcd.20054">I-graphs and the corresponding configurations</a> J. Combin. Des. 13 (2005), no. 6, 406--424.
%H M. Watkins, <a href="https://doi.org/10.1016/S0021-9800(69)80116-X">A theorem on Tait colorings with an application to the generalized Petersen graphs</a>, J. Combin. Theory 6 (1969), 152-164.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphExpansion.html">Graph Expansion</a>
%Y Cf. A077105, A153846.
%K nonn
%O 3,3
%A _Tomaz Pisanski_, Jan 08 2009