Number of tilings of a 4 X n rectangle using right trominoes and 2 X 2 tiles.

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =6a(5) =16a(6) =37a(7) =92a(8) =245a(9) =560a(10) =1426a(11) =3720a(12) =9069a(13) =22808a(14) =58177a(15) =145660a(16) =366318a(17) =925536a(18) =2331269a(19) =5872212a(20) =14802941a(21) =37311528a(22) =94038250a(23) =236999064a(24) =597348237a(25) =1505640016a(26) =3794761257a(27) =9564393972a(28) =24106951622a(29) =60759989040