Number of n X 3 0..1 arrays avoiding 0 0 0 horizontally and 0 1 1 vertically.

Terms

a(0) =7a(1) =49a(2) =211a(3) =811a(4) =2791a(5) =9055a(6) =28081a(7) =84403a(8) =247705a(9) =713857a(10) =2027929a(11) =5695201a(12) =15845455a(13) =43747201a(14) =120004363a(15) =327401947a(16) =889103743a(17) =2404885423a(18) =6482464537a(19) =17421401395a(20) =46696588561a(21) =124877198881a(22) =333267920209a(23) =887801858209