The optimal Gram matrix
For order 26 there is a known D-optimal gram matrix which is unique up to
symmetric signed permutations. It is given
here in compressed format,
and in full here
on Will Orrick's website.
Generators for 18 ST-classes
Generators for the 18 known ST-classes are given
here. From these generators one
can find 5049 HT-classes of maxdet matrices using the operations
of row/column switching and taking duals (transposes). This gives
9923 Hadamard equivalence classes of solutions with determinant
All 9923 H-classes of solutions
The complete set of all 9923 known Hadamard equivalence classes is
available here as a gzipped text file.