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Linear AlgebraSuperchallengeMatrices & Systems

Matrices & Systems · Superchallenge problem

Let AA be the 2026×20262026\times 2026 matrix with aij=1a_{ij} = 1 when ∣i−j∣=1|i - j| = 1 and aij=0a_{ij} = 0 otherwise (ones just above and just below the diagonal, zeros elsewhere). AA is invertible. Find the sum of all the entries of A−1A^{-1}.