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

Terms

a(0) =1a(1) =1a(2) =3a(3) =5a(4) =19a(5) =74a(6) =209a(7) =572a(8) =1479a(9) =4304a(10) =13002a(11) =38315a(12) =109651a(13) =308982a(14) =884120a(15) =2560952a(16) =7428183a(17) =21413028a(18) =61433280a(19) =176415916a(20) =507985116a(21) =1464725431a(22) =4220293147a(23) =12145885239a(24) =34945690653a(25) =100586823613a(26) =289649303130a(27) =834087280681