Number of ways to tile a 5 X n area with 1 X 1 and 2 X 2 tiles.

Terms

a(0) =1a(1) =1a(2) =8a(3) =21a(4) =93a(5) =314a(6) =1213a(7) =4375a(8) =16334a(9) =59925a(10) =221799a(11) =817280a(12) =3018301a(13) =11134189a(14) =41096528a(15) =151643937a(16) =559640289a(17) =2065192514a(18) =7621289593a(19) =28124714395a(20) =103789150046a(21) =383013144129