Number of tilings of a 5 X n rectangle using n pentominoes of shapes T, W, I, X.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =6a(8) =9a(9) =12a(10) =16a(11) =21a(12) =41a(13) =66a(14) =106a(15) =156a(16) =219a(17) =364a(18) =558a(19) =930a(20) =1444a(21) =2191a(22) =3515a(23) =5361a(24) =8737a(25) =13661a(26) =21478a(27) =34397a(28) =53528a(29) =86137