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

Terms

a(0) =50a(1) =314a(2) =314a(3) =1970a(4) =4594a(5) =1970a(6) =12362a(7) =66658a(8) =66658a(9) =12362a(10) =77570a(11) =969978a(12) =2235330a(13) =969978a(14) =77570a(15) =486746a(16) =14100346a(17) =75166498a(18) =75166498a(19) =14100346a(20) =486746a(21) =3054290a(22) =205047906a(23) =2525447442a(24) =5848268518a(25) =2525447442a(26) =205047906a(27) =3054290a(28) =19165418