Number of tilings of a 2 X n rectangle with dominoes and long L-shaped 4-minoes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =15a(5) =32a(6) =79a(7) =185a(8) =422a(9) =987a(10) =2307a(11) =5352a(12) =12451a(13) =29005a(14) =67478a(15) =156991a(16) =365391a(17) =850304a(18) =1978615a(19) =4604465a(20) =10715078a(21) =24934611a(22) =58024779a(23) =135028632a(24) =314222011a(25) =731218981a(26) =1701605078a(27) =3959769367a(28) =9214694391a(29) =21443322032