Levent Alpöge shared an example of all previously unknown sizes of Hadamard matrix up to 2000

levent on 𝕏: x.com/alpoge/status/2087504785952182273 Epoch AI: Hadamard Matrix of Order 668: epoch.ai/frontiermath/open-problems/hadamard Hadamard matrix - Wikipedia: en.wikipedia.org/wiki/Hadamard_matrix