A059476 Number of 4n X 4n quarter-turn symmetric alternating-sign matrices (QTSASM's).

1, 2, 40, 6860, 9779616, 114640611228, 10995014015567296, 8604220484134405095680, 54849585336544518476372715520, 2845241019832977820277705514596768000, 1200139922362764777157943140382976769515000000

Offset: 0

Author

N. J. A. Sloane, Feb 04 2001

Keywords

• nonn

Links

• G. Kuperberg, Symmetry classes of alternating-sign matrices under one roof, arXiv:math/0008184 [math.CO], 2000-2001.

Formula

a(n) = A059475(n)*A005130(n)^2.