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

Terms

a(0) =1a(1) =2a(2) =3a(3) =0a(4) =5a(5) =-2a(6) =7a(7) =-4a(8) =9a(9) =-6a(10) =11a(11) =-8a(12) =13a(13) =-10a(14) =15a(15) =-12a(16) =17a(17) =-14a(18) =19a(19) =-16a(20) =21a(21) =-18a(22) =23a(23) =-20a(24) =25a(25) =-22a(26) =27a(27) =-24a(28) =29a(29) =-26