%I #12 Mar 31 2022 22:00:17
%S 0,0,0,0,1,5,52,771,21025
%N Number of pairs of n-node simple graphs that are isospectral (excluding triples, etc.).
%H Jürgen Jost, Raffaella Mulas, and Leo Torres, <a href="https://arxiv.org/abs/2203.10824">Spectral theory of the non-backtracking Laplacian for graphs</a>, arXiv:2203.10824 [math.SP], 2022.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/IsospectralGraphs.html">Isospectral Graphs</a>
%Y Cf. A099882, A006608.
%K nonn,more
%O 1,6
%A _Eric W. Weisstein_, Oct 28 2004