a(n)= -3a(n-1)-3a(n-2)-2a(n-3), n>3. a(0)=4, a(1)=4, a(2)=-5, a(3)=4.

Terms

a(0) =4a(1) =4a(2) =-5a(3) =4a(4) =-5a(5) =13a(6) =-32a(7) =67a(8) =-131a(9) =256a(10) =-509a(11) =1021a(12) =-2048a(13) =4099a(14) =-8195a(15) =16384a(16) =-32765a(17) =65533a(18) =-131072a(19) =262147a(20) =-524291a(21) =1048576a(22) =-2097149a(23) =4194301a(24) =-8388608a(25) =16777219a(26) =-33554435a(27) =67108864a(28) =-134217725a(29) =268435453