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

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =2a(5) =2a(6) =8a(7) =0a(8) =22a(9) =40a(10) =134a(11) =100a(12) =266a(13) =448a(14) =1610a(15) =2454a(16) =4806a(17) =7064a(18) =19774a(19) =38320a(20) =81174a(21) =128604a(22) =277540a(23) =553762a(24) =1222204a(25) =2210510a(26) =4352240a(27) =8339138a(28) =17869740a(29) =34938578