A182510 a(0)=0, a(1)=1, a(n)=(a(n-1) XOR n) - a(n-2).

0, 1, 3, -1, -8, -2, 0, 9, 1, -1, -12, 0, 24, 21, 3, -9, -28, -2, 8, 29, 1, -9, -32, 0, 56, 33, 3, -9, -24, -2, -8, -23, -47, 7, 84, 112, 0, -75, -109, -1, 68, 110, 0, -67, -111, -1, 64, 112, 0, -63, -13, -1, -40, -18, 0, 73, 113, -1, -172, -144, -8, 85, 115

Offset

0,3

Comments

Conjectures: the sequence contains 8 zeros, and more positive terms than negative.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 0..10000

Formula

a(0)=0, a(1)=1, a(n)=(a(n-1) XOR n) - a(n-2), where XOR is the bitwise exclusive-or operator.

Prog

(Python)
prpr = 0
prev = 1
for n in range(2, 99):
  current = (prev ^ n) - prpr
  print prpr,
  prpr = prev
  prev = current
(PARI) v=vector(100); v[1]=0; v[2]=1; for(i=3, #v, v[i]=bitxor(v[i-1], i-1)-v[i-2]); v \\ Charles R Greathouse IV, May 03 2012

Crossrefs

Cf. A182509.

Sequence in context: A319045 A347134 A360705 * A112420 A010288 A143291

Adjacent sequences: A182507 A182508 A182509 * A182511 A182512 A182513

Keyword

sign,easy

Author

Alex Ratushnyak, May 03 2012

Status

approved