A Recursively Differentiable Quasigroup of Order 14

We construct a quasigroup of order 14 whose first recursive derivative is again a quasigroup. Equivalently, we obtain a full recursive [4,2,3]₁₄ MDS code, settling the order-14 case of the conjecture of González, Couselo, Markov, and Nechaev. The construction uses one permutation of ℤ₁₃ ∪ {∞}, and two displacement lists give a concise certificate. Thus order 18 is the sole remaining case of the conjecture. The accompanying source archive contains the LaTeX manuscript, an exhaustive Python verifier, and a Lean 4.27 formal certificate.