Number of length-n 0..3 arrays with no repeated value equal to the previous repeated value.

A269462

Number of length-n 0..3 arrays with no repeated value equal to the previous repeated value.

Terms

    a(0) =4a(1) =16a(2) =60a(3) =228a(4) =852a(5) =3180a(6) =11796a(7) =43644a(8) =160980a(9) =592572a(10) =2177268a(11) =7988700a(12) =29277204a(13) =107195196a(14) =392179380a(15) =1433907228a(16) =5240022612a(17) =19140884220a(18) =69894090996a(19) =255150047964a(20) =931214323860

External references