Number of (2n) X (2n) symmetric matrices each of whose rows is a permutation of 1..(2n).

A036980

Number of (2n) X (2n) symmetric matrices each of whose rows is a permutation of 1..(2n).

Terms

    a(0) =1a(1) =2a(2) =96a(3) =328320a(4) =440952422400

External references