Number of (n+1) X 8 0..2 arrays with every 2 X 2 subblock summing to 4.

Terms

a(0) =7075a(1) =8109a(2) =10195a(3) =14421a(4) =23035a(5) =40749a(6) =77635a(7) =155781a(8) =325195a(9) =703389a(10) =1577875a(11) =3681141a(12) =8950555a(13) =22678029a(14) =59698915a(15) =162438501a(16) =454011115a(17) =1295436669a(18) =3753128755a(19) =10993035861a(20) =32446418875a(21) =96273891309a(22) =286690955395