A036980 - OEIS

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A036980

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

%I #11 May 05 2023 09:26:54

%S 1,2,96,328320,440952422400

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

%F a(n) = A035483(n) * (2n)!

%Y Cf. A035481, A036981.

%K more,nonn

%O 0,2

%A _Joshua Zucker_ and Joe Keane