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

Terms

a(0) =3a(1) =0a(2) =9a(3) =6a(4) =39a(5) =24a(6) =153a(7) =102a(8) =615a(9) =408a(10) =2457a(11) =1638a(12) =9831a(13) =6552a(14) =39321a(15) =26214a(16) =157287a(17) =104856a(18) =629145a(19) =419430a(20) =2516583a(21) =1677720a(22) =10066329a(23) =6710886a(24) =40265319a(25) =26843544a(26) =161061273a(27) =107374182a(28) =644245095a(29) =429496728