1/4 the number of (n+1) X 8 binary arrays with all 2 X 2 subblock sums the same.

Terms

a(0) =81a(1) =83a(2) =86a(3) =92a(4) =102a(5) =122a(6) =158a(7) =230a(8) =366a(9) =638a(10) =1166a(11) =2222a(12) =4302a(13) =8462a(14) =16718a(15) =33230a(16) =66126a(17) =131918a(18) =263246a(19) =525902a(20) =1050702a(21) =2100302a(22) =4198478a(23) =8394830a(24) =16785486a(25) =33566798a(26) =67125326a(27) =134242382a(28) =268468302a(29) =536920142