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

Terms

a(0) =22a(1) =158a(2) =666a(3) =2111a(4) =5548a(5) =12752a(6) =26494a(7) =50863a(8) =91634a(9) =156682a(10) =256442a(11) =404415a(12) =617720a(13) =917692a(14) =1330526a(15) =1887967a(16) =2628046a(17) =3595862a(18) =4844410a(19) =6435455a(20) =8440452a(21) =10941512a(22) =14032414a(23) =17819663a(24) =22423594a(25) =27979522a(26) =34638938a(27) =42570751a(28) =51962576