Number of nX1 0..3 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor.

A203094

Number of nX1 0..3 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor.

Terms

    a(0) =1a(1) =4a(2) =16a(3) =50a(4) =144a(5) =422a(6) =1268a(7) =3823a(8) =11472a(9) =34350a(10) =102896a(11) =308419a(12) =924532a(13) =2771101a(14) =8305373a(15) =24892609a(16) =74608516a(17) =223618304a(18) =670231838a(19) =2008825312a(20) =6020872062a(21) =18045827096a(22) =54087163859a(23) =162110668160a(24) =485879938474

External references