a(n) = Sum_{k=1..n-1} k XOR n-k.

Terms

a(0) =0a(1) =6a(2) =4a(3) =12a(4) =20a(5) =42a(6) =32a(7) =40a(8) =48a(9) =78a(10) =84a(11) =116a(12) =148a(13) =210a(14) =176a(15) =176a(16) =176a(17) =214a(18) =212a(19) =252a(20) =292a(21) =378a(22) =368a(23) =408a(24) =448a(25) =542a(26) =580a(27) =676a(28) =772a(29) =930