Number of 0..3 arrays x(0..n+1) of n+2 elements without any interior element greater than both neighbors.

A200881

Number of 0..3 arrays x(0..n+1) of n+2 elements without any interior element greater than both neighbors.

Terms

    a(0) =50a(1) =144a(2) =422a(3) =1268a(4) =3823a(5) =11472a(6) =34350a(7) =102896a(8) =308419a(9) =924532a(10) =2771101a(11) =8305373a(12) =24892609a(13) =74608516a(14) =223618304a(15) =670231838a(16) =2008825312a(17) =6020872062a(18) =18045827096a(19) =54087163859a(20) =162110668160a(21) =485879938474

External references