Number of n X 2 0..1 arrays with row sums and column sums unimodal.

Terms

a(0) =4a(1) =16a(2) =53a(3) =155a(4) =418a(5) =1066a(6) =2611a(7) =6205a(8) =14408a(9) =32852a(10) =73825a(11) =163951a(12) =360574a(13) =786574a(14) =1704095a(15) =3670193a(16) =7864516a(17) =16777432a(18) =35651821a(19) =75497731a(20) =159383834a(21) =335544626a(22) =704643403a(23) =1476395365a(24) =3087008128a(25) =6442451356a(26) =13421773241a(27) =27917287895