Number of nX4 0..1 arrays with each 1 adjacent to 3 or 5 king-move neighboring 1s.

Terms

a(0) =1a(1) =7a(2) =16a(3) =32a(4) =91a(5) =237a(6) =585a(7) =1513a(8) =3908a(9) =10086a(10) =26367a(11) =68437a(12) =178447a(13) =471619a(14) =1236166a(15) =3249228a(16) =8644925a(17) =22840435a(18) =60474807a(19) =161669767a(20) =429688556a(21) =1144258358a(22) =3069721963a(23) =8195327679a(24) =21917660229a(25) =58944562187a(26) =157891940442a(27) =423580112950