Binary XOR of (2^k - (-1)^k)/3 as k varies from 1 to n.

Terms

a(0) =1a(1) =0a(2) =3a(3) =6a(4) =13a(5) =24a(6) =51a(7) =102a(8) =205a(9) =408a(10) =819a(11) =1638a(12) =3277a(13) =6552a(14) =13107a(15) =26214a(16) =52429a(17) =104856a(18) =209715a(19) =419430a(20) =838861a(21) =1677720a(22) =3355443a(23) =6710886a(24) =13421773a(25) =26843544a(26) =53687091a(27) =107374182a(28) =214748365a(29) =429496728