A263624 Number of Seidel matrices of order n with exactly three distinct eigenvalues, up to switching equivalence.

0, 0, 1, 2, 0, 2, 3, 4, 0, 10

Offset

3,4

Links

Table of n, a(n) for n=3..12.

G. Greaves, J. H. Koolen, A. Munemasa, F. Szöllősi, Equiangular lines in Euclidean spaces, arXiv:1403.2155 [math.CO], 2014.

Crossrefs

Sequence in context: A245230 A284268 A063180 * A141693 A279679 A261096

Adjacent sequences: A263621 A263622 A263623 * A263625 A263626 A263627

Keyword

nonn,more

Author

N. J. A. Sloane, Oct 24 2015

Status

approved