Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its west or northeast neighbor modulo 3 and the upper left element equal to 0.

A266868

Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its west or northeast neighbor modulo 3 and the upper left element equal to 0.

Terms

    a(0) =2a(1) =4a(2) =17a(3) =57a(4) =207a(5) =786a(6) =3057a(7) =12168a(8) =49161a(9) =200973a(10) =830381a(11) =3462433a(12) =14543365a(13) =61455313a(14) =261051074a(15) =1114132113a(16) =4775036853a(17) =20540793414a(18) =88645205402a(19) =383652117835

External references