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A272659
Number of distinct characteristic polynomials of n X n matrices with elements {0, 1, 2}.
15
1, 3, 22, 513, 58335, 40422490
OFFSET
0,2
LINKS
Robert M. Corless, Bohemian Eigenvalues, Talk Presented at Computational Discovery in Mathematics (ACMES 2), University of Western Ontario, May 12 2016. (Talk based on joint work with Steven E. Thornton, Sonia Gupta, Jonathan Brino-Tarasoff, Venkat Balasubramanian.)
PROG
(Python)
from itertools import product
from sympy import Matrix
def A272659(n): return len({tuple(Matrix(n, n, p).charpoly().as_list()) for p in product(range(3), repeat=n**2)}) if n else 1 # Chai Wah Wu, Sep 30 2023
CROSSREFS
Six classes of matrices mentioned in Rob Corless's talk: A272658, A272659, A272660, A272661, A272662, A272663.
Sequence in context: A364844 A156512 A119770 * A233748 A153230 A195462
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, May 15 2016
EXTENSIONS
a(4) from Chai Wah Wu, Dec 03 2018
a(5) from Steven E. Thornton, Mar 09 2019
a(0)=1 prepended by Alois P. Heinz, Sep 28 2023
STATUS
approved