Number of inequivalent tilings of a 3 X n rectangle using integer-sided square tiles.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =10a(6) =21a(7) =39a(8) =82a(9) =163a(10) =347a(11) =717a(12) =1533a(13) =3232a(14) =6927a(15) =14748a(16) =31645a(17) =67690a(18) =145322a(19) =311535a(20) =668997a(21) =1435645a(22) =3083301a(23) =6619842a(24) =14218066a(25) =30533005a(26) =65580338a(27) =140847132a(28) =302522253a(29) =649759735