A140421 Number of n X n symmetric binary matrices with every element adjacent to some zero horizontally or vertically.

3, 13, 160, 2817, 119145, 8890880, 1270451663, 347961207321, 183722336587008, 185316870246113925, 357804006282379850529, 1323503980097432239521792, 9379216327375443934023725295, 127291943357342220975708211213101