a(0) = 0, a(1) = 1; for n > 1, a(n) = Sum_{k=0..n-2} a(k) XOR a(n-k-2).

Terms

a(0) =0a(1) =1a(2) =0a(3) =2a(4) =0a(5) =6a(6) =6a(7) =18a(8) =26a(9) =66a(10) =110a(11) =242a(12) =450a(13) =922a(14) =1826a(15) =3674a(16) =7290a(17) =14586a(18) =29178a(19) =58410a(20) =116538a(21) =233258a(22) =466114a(23) =932426a(24) =1864586a(25) =3729274a(26) =7457386a(27) =14915578a(28) =29828762a(29) =59659322