A035483 - cp's OEIS frontend

A035483 Number of 2n X 2n symmetric matrices whose first row is 1..2n and whose rows and columns are all permutations of 1..2n.

%I A035483 #25 Jun 17 2022 03:18:24
%S A035483 1,1,4,456,10936320,130025295912960,2209617218725251404267520
%N A035483 Number of 2n X 2n symmetric matrices whose first row is 1..2n and whose rows and columns are all permutations of 1..2n.
%F A035483 a(n) = A035481(2*n). - _Max Alekseyev_, Apr 23 2010
%Y A035483 Cf. A000438, A035481, A000315, A002860, A003090, A040082.
%K A035483 more,nonn,nice
%O A035483 0,3
%A A035483 _Joshua Zucker_ and Joe Keane
%E A035483 a(5)-a(6) from _Ian Wanless_, Oct 20 2019

cp's OEIS Frontend

A035483 Number of 2n X 2n symmetric matrices whose first row is 1..2n and whose rows and columns are all permutations of 1..2n.