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

Terms

a(0) =0a(1) =0a(2) =-1a(3) =2a(4) =-1a(5) =7a(6) =2a(7) =21a(8) =15a(9) =60a(10) =59a(11) =167a(12) =194a(13) =457a(14) =587a(15) =1236a(16) =1695a(17) =3315a(18) =4754a(19) =8837a(20) =13079a(21) =23452a(22) =35507a(23) =62031a(24) =95490a(25) =163665a(26) =255059a(27) =431012a(28) =677879a(29) =1133467