a(n) is the binary XOR of all n-bit squares, with a(2)=0 indicating that no 2-bit squares exist.

Terms

a(0) =1a(1) =0a(2) =4a(3) =9a(4) =9a(5) =21a(6) =12a(7) =28a(8) =449a(9) =577a(10) =357a(11) =997a(12) =6085a(13) =14533a(14) =12517a(15) =15077a(16) =121125a(17) =152869a(18) =400028a(19) =1041052a(20) =1290704a(21) =2556368a(22) =4913664a(23) =11950592a(24) =22421376a(25) =63692672a(26) =7674753a(27) =78355329a(28) =312723717a(29) =656197893