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

Terms

a(0) =0a(1) =0a(2) =1a(3) =-1a(4) =0a(5) =2a(6) =-3a(7) =1a(8) =4a(9) =-8a(10) =5a(11) =7a(12) =-20a(13) =18a(14) =9a(15) =-47a(16) =56a(17) =0a(18) =-103a(19) =159a(20) =-56a(21) =-206a(22) =421a(23) =-271a(24) =-356a(25) =1048a(26) =-963a(27) =-441a(28) =2452a(29) =-2974