Number of tilings of a 3 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =8a(7) =13a(8) =19a(9) =35a(10) =58a(11) =89a(12) =154a(13) =256a(14) =405a(15) =681a(16) =1131a(17) =1822a(18) =3025a(19) =5012a(20) =8156a(21) =13465a(22) =22257a(23) =36415a(24) =59976a(25) =98961a(26) =162370a(27) =267184a(28) =440335a(29) =723521