Number of n X 2 0..1 arrays with each 1 adjacent to 1, 3 or 5 king-move neighboring 1s.

Terms

a(0) =2a(1) =8a(2) =16a(3) =36a(4) =112a(5) =256a(6) =608a(7) =1680a(8) =4064a(9) =9920a(10) =25984a(11) =64320a(12) =159232a(13) =407296a(14) =1017344a(15) =2536704a(16) =6420992a(17) =16093184a(18) =40271872a(19) =101471232a(20) =254636032a(21) =638328832a(22) =1605165056a(23) =4029763584a(24) =10110525440a(25) =25402425344a(26) =63780978688a(27) =160088997888