The number of tilings of a 6 X n floor with 1 X 3 trominoes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =6a(4) =13a(5) =22a(6) =64a(7) =155a(8) =321a(9) =783a(10) =1888a(11) =4233a(12) =9912a(13) =23494a(14) =54177a(15) =126019a(16) =295681a(17) =687690a(18) =1600185a(19) =3738332a(20) =8712992a(21) =20293761a(22) =47337405a(23) =110368563a(24) =257206012a(25) =599684007a(26) =1398149988a(27) =3259051800a(28) =7597720649a(29) =17712981963