A127988 Sequence determining the parity of A025748.

0, 8, 32, 40, 128, 136, 160, 168, 512, 520, 544, 552, 640, 648, 672, 680, 2048, 2056, 2080, 2088, 2176, 2184, 2208, 2216, 2560, 2568, 2592, 2600, 2688, 2696, 2720, 2728, 8192, 8200, 8224, 8232, 8320, 8328, 8352, 8360, 8704, 8712, 8736

Offset: 0

Author

Paul Barry, Feb 09 2007

Keywords

• easy
• nonn

Comments

Odd terms occur in A025748 at positions (0),1,2,3,(8),9,10,11,(32),33,34,35,(40),...

Formula

a(n)=8*A000695(n); a(n)=4*sum{k=0..floor(log_2(n+1)), mod(floor(n/2^k),2)2^(2k+1)};