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A006608 Number of n-node graphs not determined by their spectrum.
(Formerly M1981)
0, 0, 0, 0, 2, 10, 110, 1722, 51039, 2560606, 215331676, 31067572481 (list; graph; refs; listen; history; text; internal format)
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
A. E. Brouwer and E. Spence, Cospectral graphs on 12 vertices, Electr. J. Combin. 16 (2009) N20. (p. 199).
C. Godsil and B. D. McKay, Some computational results on the spectra of graphs, pp. 73-92 of Combinatorial Mathematics IV (Adelaide 1975), Lect. Notes Math., 560 (1976).
Andreas Holmstrom, A first step towards automated conjecture-making in higher arithmetic geometry, Work-in-progress paper presented at the Conference on Intelligent Computer Mathematics, July 2016. Published in the CEUR Workshop Proceedings.
Jürgen Jost, Raffaella Mulas, and Leo Torres, Spectral theory of the non-backtracking Laplacian for graphs, arXiv:2203.10824 [math.SP], 2022.
P. W. Mills, R. P. Rundle, J. H. Samson, Simon J. Devitt, Todd Tilma, V. M. Dwyer and Mark J. Everitt, Quantum invariants and the graph isomorphism problem, Phys. Rev. A 100, 052317 (2019).
Eric Weisstein's World of Mathematics, Determined by Spectrum
Eric Weisstein's World of Mathematics, Isospectral Graphs
Cf. A178925 (simple graphs determined by spectrum), A099881, A099882.
Sequence in context: A062412 A212491 A364409 * A066205 A113147 A335946
a(10) from Eric W. Weisstein, Dec 30 2010
Two more terms from Ruperto Corso, Dec 18 2011

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Last modified October 3 22:39 EDT 2023. Contains 365872 sequences. (Running on oeis4.)