Real part of upper left and lower right terms of [1,(1+I); 1,1]^n * [1,0].

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =11a(5) =14a(6) =8a(7) =-31a(8) =-167a(9) =-558a(10) =-1572a(11) =-4025a(12) =-9645a(13) =-21922a(14) =-47536a(15) =-98431a(16) =-193935a(17) =-360094a(18) =-617100a(19) =-929593a(20) =-1056037a(21) =-145682a(22) =4258520a(23) =18546401a(24) =58207561a(25) =158790322a(26) =398072524a(27) =938582407a(28) =2103831971a(29) =4502207934