T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock summing to 5 6 or 7.

Terms

a(0) =124a(1) =1048a(2) =1048a(3) =9124a(4) =19644a(5) =9124a(6) =80296a(7) =385704a(8) =385704a(9) =80296a(10) =709396a(11) =7712232a(12) =17309672a(13) =7712232a(14) =709396a(15) =6276040a(16) =155378004a(17) =796635224a(18) =796635224a(19) =155378004a(20) =6276040a(21) =55551652a(22) =3140670344a(23) =37078015004a(24) =84953563232a(25) =37078015004