Number of n X 2 0..1 arrays with each 1 adjacent to 2 or 4 king-move neighboring 1s.

Terms

a(0) =1a(1) =5a(2) =11a(3) =21a(4) =55a(5) =125a(6) =271a(7) =645a(8) =1479a(9) =3325a(10) =7695a(11) =17653a(12) =40183a(13) =92269a(14) =211487a(15) =483365a(16) =1107591a(17) =2537245a(18) =5806511a(19) =13298005a(20) =30454935a(21) =69724365a(22) =159661375a(23) =365617029a(24) =837155239a(25) =1916943229a(26) =4389542863a(27) =10051119797a(28) =23015247287a(29) =52701125421