Number of domino tilings of 4 X (n-1) board.

Terms

a(0) =0a(1) =1a(2) =1a(3) =5a(4) =11a(5) =36a(6) =95a(7) =281a(8) =781a(9) =2245a(10) =6336a(11) =18061a(12) =51205a(13) =145601a(14) =413351a(15) =1174500a(16) =3335651a(17) =9475901a(18) =26915305a(19) =76455961a(20) =217172736a(21) =616891945a(22) =1752296281a(23) =4977472781a(24) =14138673395a(25) =40161441636a(26) =114079985111a(27) =324048393905