Number of ways to tile a 4 X n region with 1 X 1, 2 X 2, 3 X 3 and 4 X 4 tiles.

Terms

a(0) =1a(1) =1a(2) =5a(3) =13a(4) =40a(5) =117a(6) =348a(7) =1029a(8) =3049a(9) =9028a(10) =26738a(11) =79183a(12) =234502a(13) =694476a(14) =2056692a(15) =6090891a(16) =18038173a(17) =53420041a(18) =158203433a(19) =468519406a(20) =1387520047a(21) =4109140098a(22) =12169216863a(23) =36039131181a(24) =106729873498a(25) =316080480394a(26) =936072224321