Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock summing to 4.

Terms

a(0) =115a(1) =189a(2) =355a(3) =741a(4) =1675a(5) =4029a(6) =10195a(7) =26901a(8) =73435a(9) =205869a(10) =588835a(11) =1709061a(12) =5012395a(13) =14807709a(14) =43964275a(15) =130975221a(16) =391090555a(17) =1169601549a(18) =3501464515a(19) =10489713381a(20) =31439779915a(21) =94260619389a(22) =282664417555a(23) =847758371541