Number of tilings of a 14 X n rectangle using 2n heptominoes of shape I.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =1a(7) =10a(8) =21a(9) =34a(10) =49a(11) =66a(12) =85a(13) =106a(14) =256a(15) =535a(16) =985a(17) =1654a(18) =2596a(19) =3871a(20) =5545a(21) =9391a(22) =16956a(23) =30589a(24) =53481a(25) =89851a(26) =145152a(27) =226297a(28) =364656a(29) =610062