T(n,k)=Half the number of (n+1)X(k+1) 0..2 arrays with every 2X2 subblock having two or four distinct clockwise edge differences.

A209511

T(n,k)=Half the number of (n+1)X(k+1) 0..2 arrays with every 2X2 subblock having two or four distinct clockwise edge differences.

Terms

    a(0) =9a(1) =27a(2) =27a(3) =81a(4) =123a(5) =81a(6) =243a(7) =561a(8) =561a(9) =243a(10) =729a(11) =2559a(12) =3906a(13) =2559a(14) =729a(15) =2187a(16) =11673a(17) =27225a(18) =27225a(19) =11673a(20) =2187a(21) =6561a(22) =53247a(23) =189801a(24) =290493a(25) =189801a(26) =53247a(27) =6561a(28) =19683a(29) =242889

External references