'Core' alternating sign n X n matrices, i.e., those that are not 'blown up' from a smaller matrix by inserting row i, column j with a_ij = 1 and all other entries in that row and column equal to 0.

A003827

'Core' alternating sign n X n matrices, i.e., those that are not 'blown up' from a smaller matrix by inserting row i, column j with a_ij = 1 and all other entries in that row and column equal to 0.