Number of ways of tiling a 2 X n rectangle with dominoes and trominoes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =17a(5) =43a(6) =108a(7) =280a(8) =727a(9) =1875a(10) =4832a(11) =12470a(12) =32191a(13) =83075a(14) =214372a(15) =553214a(16) =1427673a(17) =3684333a(18) =9507936a(19) =24536616a(20) =63320419a(21) =163407771a(22) =421697922a(23) =1088253936a(24) =2808400703a(25) =7247494517a(26) =18703234038a(27) =48266468208a(28) =124558777387a(29) =321442392689