One quarter the number of nX9 1..4 arrays with no two neighbors of any element equal to each other.

A183361

One quarter the number of nX9 1..4 arrays with no two neighbors of any element equal to each other.

Terms

    a(0) =8748a(1) =589824a(2) =314928a(3) =435600a(4) =802944a(5) =1679616a(6) =3852288a(7) =9437184a(8) =23003136a(9) =47775744a(10) =95551488a(11) =191102976a(12) =389283840a(13) =807469056a(14) =1695744000a(15) =3588489216a(16) =7596343296a(17) =16057958400a(18) =33888927744a(19) =71430045696a(20) =150473539584

External references