T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock singular.

Terms

a(0) =64a(1) =424a(2) =424a(3) =2248a(4) =8272a(5) =2248a(6) =13096a(7) =108496a(8) =108496a(9) =13096a(10) =73288a(11) =1792144a(12) =1967440a(13) =1792144a(14) =73288a(15) =417256a(16) =27993232a(17) =62051344a(18) =62051344a(19) =27993232a(20) =417256a(21) =2358280a(22) =454774672a(23) =1444491280a(24) =4975179472a(25) =1444491280a(26) =454774672a(27) =2358280