Number of 3 X n 0..2 arrays with diagonals and antidiagonals unimodal and rows nondecreasing.

Terms

a(0) =27a(1) =216a(2) =788a(3) =2321a(4) =5840a(5) =13052a(6) =26610a(7) =50423a(8) =90012a(9) =152912a(10) =249120a(11) =391589a(12) =596768a(13) =885188a(14) =1282094a(15) =1818123a(16) =2530028a(17) =3461448a(18) =4663724a(19) =6196761a(20) =8129936a(21) =10543052a(22) =13527338a(23) =17186495a(24) =21637788a(25) =27013184a(26) =33460536a(27) =41144813a(28) =50249376