Number of length-n 0..3 arrays with no adjacent pair x,x+1 repeated.

A269651

Number of length-n 0..3 arrays with no adjacent pair x,x+1 repeated.

Terms

    a(0) =4a(1) =16a(2) =64a(3) =253a(4) =988a(5) =3816a(6) =14596a(7) =55344a(8) =208196a(9) =777582a(10) =2885120a(11) =10640607a(12) =39027196a(13) =142415244a(14) =517252820a(15) =1870499543a(16) =6736838192a(17) =24172420350a(18) =86428990624a(19) =308016010824

External references