Number of length n+4 0..2 arrays with at most one downstep in every n consecutive neighbor pairs.

Terms

a(0) =243a(1) =622a(2) =1137a(3) =1905a(4) =2951a(5) =4338a(6) =6141a(7) =8448a(8) =11361a(9) =14997a(10) =19489a(11) =24987a(12) =31659a(13) =39692a(14) =49293a(15) =60690a(16) =74133a(17) =89895a(18) =108273a(19) =129589a(20) =154191a(21) =182454a(22) =214781a(23) =251604a(24) =293385a(25) =340617a(26) =393825a(27) =453567a(28) =520435a(29) =595056