A199396 Binary XOR of (3^k - 1)/2 as k varies from 1 to n.

1, 5, 8, 32, 89, 309, 1392, 2464, 12241, 23685, 66936, 329856, 598377, 2972885, 4204000, 17321536, 47254689, 156943365, 737779176, 1276350496, 6369950073, 12290868597, 35051319632, 175157734688, 319624706161, 1569854375813, 2311734655064, 9333158201280, 25600877525257

Offset: 1

Author

Paul D. Hanna, Nov 05 2011

Keywords

• nonn

Examples

			a(2) = (3^1-1)/2 XOR (3^2-1)/2 = 1 XOR 4 = 5;
a(3) = (3^1-1)/2 XOR (3^2-1)/2 XOR (3^3-1)/2 = 1 XOR 4 XOR 13 = 8;
a(4) = (3^1-1)/2 XOR (3^2-1)/2 XOR (3^3-1)/2 XOR (3^4-1)/2 = 1 XOR 4 XOR 13 XOR 40 = 32.
		

Links

• Paul D. Hanna, Table of n, a(n) for n = 1..365

Crossrefs

Cf. A199397, A199403, A199402, A000975.

Programs

Mathematica

FoldList[BitXor, Table[(3^n - 1)/2, {n, 1, 29}]] (* Vladimir Reshetnikov, Nov 02 2015 *)

PARI

{a(n)=if(n<=0,0,bitxor(a(n-1),(3^n-1)/2))}