|
%I #10 Nov 28 2017 06:43:53
%S 1,2,80,53760,590413824,104981650735104,300931721514121691136,
%T 13874404129378738693891686400,10274196157891080769280680484929536000,
%U 122089077024940067215877965611538507917950976000,23266604385482749027479729551862778584550130343015874560000
%N Number of 2-enumeration of 4n X 4n quarter-turn symmetric alternating-sign matrices.
%H G. Kuperberg, <a href="https://arxiv.org/abs/math/0008184">Symmetry classes of alternating-sign matrices under one roof</a>, arXiv:math/0008184 [math.CO], 2000-2001; [Th. 3].
%p A059487 := proc(n) local i, j, t1; t1 := (-1)^(n*(n-1)/2)*2^(2*n^2-n); for i to n do for j to n do t1 := t1*(4*j - 4*i + 1)/(j - i + n); end do end do; t1 end proc;
%t a[n_] := Module[{t1 = (-1)^(n*(n - 1)/2)*2^(2*n^2 - n)}, Do[t1 = t1*(4*j - 4*i + 1)/(j - i + n), {j, n}, {i, n}]; t1];
%t Array[a, 11, 0] (* _Jean-François Alcover_, Nov 28 2017, from Maple *)
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, Feb 04 2001
|
