Number of tilings of a 4 X n rectangle using L and Z tetrominoes.

Terms

a(0) =1a(1) =0a(2) =2a(3) =6a(4) =14a(5) =32a(6) =102a(7) =238a(8) =652a(9) =1696a(10) =4480a(11) =11658a(12) =30870a(13) =80644a(14) =212292a(15) =556858a(16) =1463390a(17) =3840686a(18) =10090218a(19) =26490280a(20) =69575414a(21) =182693434a(22) =479789138a(23) =1259906496a(24) =3308668718a(25) =8688615148a(26) =22817011182a(27) =59918425698a(28) =157349755400a(29) =413208421354