Number of n X 3 binary arrays with each 1 adjacent to exactly two 0's.

Terms

a(0) =2a(1) =10a(2) =26a(3) =66a(4) =194a(5) =534a(6) =1468a(7) =4102a(8) =11402a(9) =31644a(10) =87958a(11) =244418a(12) =679050a(13) =1886836a(14) =5242786a(15) =14567272a(16) =40476178a(17) =112465998a(18) =312494040a(19) =868285644a(20) =2412590548a(21) =6703544510a(22) =18626248566a(23) =51754284540a(24) =143802757136a(25) =399565623778