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A352478
a(n) is the number of Toeplitz anti-Hadamard matrices of order n whose sum of the inverse squares of their singular values is maximal.
0
1, 2, 3, 6, 4, 2, 2, 2, 2, 2, 2, 12
OFFSET
1,2
COMMENTS
Conjecture: a(1) = 1 and a(3) = 3 are the only odd terms.
LINKS
R. L. Graham and N. J. A. Sloane, Anti-Hadamard matrices, Linear Alg. Applic., 62 (1984), 113-137.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Stefano Spezia, Mar 17 2022
STATUS
approved