a(0)=2, a(1)=5, a(n+2) = a(n+1) + (-1)^n a(n).

Terms

a(0) =2a(1) =5a(2) =7a(3) =2a(4) =9a(5) =7a(6) =16a(7) =9a(8) =25a(9) =16a(10) =41a(11) =25a(12) =66a(13) =41a(14) =107a(15) =66a(16) =173a(17) =107a(18) =280a(19) =173a(20) =453a(21) =280a(22) =733a(23) =453a(24) =1186a(25) =733a(26) =1919a(27) =1186a(28) =3105a(29) =1919