a(n) = a(n-1) + 2*a(n-2) + 8*Fibonacci(n) + 2*Fibonacci(n-1); a(1) = 4, a(2) = 14.

Terms

a(0) =4a(1) =14a(2) =40a(3) =96a(4) =222a(5) =488a(6) =1052a(7) =2222a(8) =4640a(9) =9592a(10) =19694a(11) =40208a(12) =81748a(13) =165646a(14) =334776a(15) =675184a(16) =1359486a(17) =2733720a(18) =5491308a(19) =11021230a(20) =22104944a(21) =44310984a(22) =88785550a(23) =177835776a(24) =356099812a(25) =712892558a(26) =1426906312a(27) =2855626752a(28) =5714188830a(29) =11433127112