The conjectured optimal Gram matrix
For order 27 there is a conjectured D-optimal gram matrix G
due to Hiroki Tamura (26 August 2005). It is given
here in compressed format,
and in full here
on Will Orrick's website.
The determinant of G is (546*6^11*2^26)^2.
Generators for 204 ST-classes
Generators for the 204 known ST-classes are given
here. From these generators one
can find 6489 HT-classes of maxdet matrices using the operations
of row/column switching and taking duals (transposes). This gives
12911 Hadamard equivalence classes of solutions with determinant
All 12911 H-classes of solutions
The complete set of all 12911 known Hadamard equivalence classes is
available here as a gzipped text file.