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

Terms

a(0) =1a(1) =1a(2) =3a(3) =5a(4) =19a(5) =74a(6) =219a(7) =628a(8) =1749a(9) =5486a(10) =17448a(11) =53383a(12) =160169a(13) =479908a(14) =1468366a(15) =4512092a(16) =13782535a(17) =41855766a(18) =127112554a(19) =387469920a(20) =1182800866a(21) =3606789463a(22) =10983721059a(23) =33445214911a(24) =101911804705a(25) =310658892951a(26) =946813182854