a(n) = -5*a(n-1) - 4*a(n-2), a(0)=1, a(1)=0.

Terms

a(0) =1a(1) =0a(2) =-4a(3) =20a(4) =-84a(5) =340a(6) =-1364a(7) =5460a(8) =-21844a(9) =87380a(10) =-349524a(11) =1398100a(12) =-5592404a(13) =22369620a(14) =-89478484a(15) =357913940a(16) =-1431655764a(17) =5726623060a(18) =-22906492244a(19) =91625968980a(20) =-366503875924