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Number of n-node simple graphs that are determined by spectrum.
1

%I #28 Feb 16 2025 08:33:12

%S 1,2,4,11,32,146,934,10624,223629,9444562,803666188,134023600111

%N Number of n-node simple graphs that are determined by spectrum.

%H A. E. Brouwer and E. Spence, <a href="https://doi.org/10.37236/258">Cospectral graphs on 12 vertices</a>, Electr. J. Combin. 16 (2009) N20.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DeterminedbySpectrum.html">Determined by Spectrum</a>

%F a(n) = A000088(n) - A006608(n).

%Y Cf. A000088, A006608 (simple graphs not determined by spectrum).

%K nonn,hard,more,changed

%O 1,2

%A _Eric W. Weisstein_, Dec 29 2010

%E a(10) from _Eric W. Weisstein_, Dec 30 2010

%E a(11)-a(12) from _Eric W. Weisstein_, Apr 11 2024 (from Brouwer and Spence)