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

Terms

a(0) =-1a(1) =-4a(2) =5a(3) =-15a(4) =31a(5) =-72a(6) =160a(7) =-361a(8) =810a(9) =-1821a(10) =4091a(11) =-9193a(12) =20656a(13) =-46414a(14) =104291a(15) =-234340a(16) =526557a(17) =-1183163a(18) =2658543a(19) =-5973692a(20) =13422764a(21) =-30160677a(22) =67770426a(23) =-152278765a(24) =342167279a(25) =-768842897a(26) =1727574308a(27) =-3881824234a(28) =8722379879a(29) =-19599009684