Number of tilings of a 2 X n rectangle using 2 X 2 and 1 X 1 tiles and right trominoes.

Terms

a(0) =1a(1) =1a(2) =6a(3) =13a(4) =45a(5) =122a(6) =373a(7) =1073a(8) =3182a(9) =9293a(10) =27349a(11) =80178a(12) =235509a(13) =691097a(14) =2028998a(15) =5955501a(16) =17482685a(17) =51318186a(18) =150642613a(19) =442198913a(20) =1298048350a(21) =3810328141a(22) =11184967717a(23) =32832705122a(24) =96378199989a(25) =282911661033a(26) =830468071222