A057629 Number of alternating sign 2n X 2n matrices invariant under flips in both diagonals.
2, 8, 52, 568, 10436, 323144, 16866856, 1484714416, 220426128584
Offset: 1
Links
- D. P. Robbins, Symmetry classes of alternating sign matrices, arXiv:math/0008045 [math.CO], 2000.
Formula
a(n) = A005162(2*n).
Extensions
a(8)-a(9) from A005162(2*n) by Jinyuan Wang, Mar 03 2020