a(n) = 7*a(n-1) + (-1)^n*6*2^(n-1).

Terms

a(0) =1a(1) =1a(2) =19a(3) =109a(4) =811a(5) =5581a(6) =39259a(7) =274429a(8) =1921771a(9) =13450861a(10) =94159099a(11) =659107549a(12) =4613765131a(13) =32296331341a(14) =226074368539