A082104 Number of distinct characteristic polynomials among all simple undirected graphs on n nodes.

1, 2, 4, 11, 33, 151, 988, 11453, 247357, 10608128, 901029366, 148187993520

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Andries E. Brouwer, Numbers of characteristic polynomials and cospectral graphs for A

A. E. Brouwer and E. Spence, Cospectral graphs on 12 vertices, Electr. J. Combin. 16 (2009) N20. (p. 199).

Lorentz Jäntschi and Sorana D. Bolboacă, Characteristic Polynomial, Chapter 7, New Frontiers in Nanochemistry, 1st ed., Apple Academic Press, 2020.

Dan-Marian Joiţa and Lorentz Jäntschi, Extending the Characteristic Polynomial for Characterization of C_20 Fullerene Congeners, Mathematics (2017), 5(4), 84.

E. Spence, Numbers of characteristic polynomials and cospectral graphs for A

Eric Weisstein's World of Mathematics, Characteristic Polynomial

Crossrefs

Cf. A000088.

Sequence in context: A052431 A076316 A304125 * A198634 A287007 A369843

Adjacent sequences: A082101 A082102 A082103 * A082105 A082106 A082107

Keyword

nonn,hard,more

Author

Eric W. Weisstein, Apr 03 2003

Extensions

One term added by Andries E. Brouwer, Apr 09 2009

Two more terms from Ruperto Corso, Dec 18 2011

Status

approved