Number of tilings of a 12 X n rectangle using 2n hexominoes of shape I.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =9a(7) =19a(8) =31a(9) =45a(10) =61a(11) =79a(12) =196a(13) =419a(14) =786a(15) =1341a(16) =2134a(17) =3221a(18) =5789a(19) =10995a(20) =20621a(21) =37149a(22) =63931a(23) =105379a(24) =180201a(25) =319826a(26) =578034a(27) =1040971a(28) =1840549a(29) =3171726