a(0)=-4; a(n+1) = 2*a(n) + period 4: repeat 6,1,2,5.

Terms

a(0) =-4a(1) =-2a(2) =-3a(3) =-4a(4) =-3a(5) =0a(6) =1a(7) =4a(8) =13a(9) =32a(10) =65a(11) =132a(12) =269a(13) =544a(14) =1089a(15) =2180a(16) =4365a(17) =8736a(18) =17473a(19) =34948a(20) =69901a(21) =139808a(22) =279617a(23) =559236a(24) =1118477a(25) =2236960a(26) =4473921a(27) =8947844a(28) =17895693a(29) =35791392