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

Terms

a(0) =-1a(1) =1a(2) =2a(3) =1a(4) =1a(5) =4a(6) =7a(7) =9a(8) =14a(9) =25a(10) =41a(11) =64a(12) =103a(13) =169a(14) =274a(15) =441a(16) =713a(17) =1156a(18) =1871a(19) =3025a(20) =4894a(21) =7921a(22) =12817a(23) =20736a(24) =33551a(25) =54289a(26) =87842a(27) =142129a(28) =229969a(29) =372100