The On-Line Encyclopedia of Integer Sequences (OEIS)

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A178753

a(n) = n XOR floor(Log_2(n))+1, where XOR is bitwise XOR.
(history; published version)

#2 by Russ Cox at Fri Mar 30 17:31:29 EDT 2012

AUTHOR

_Robert G. Wilson v (rgwv(AT)rgwv.com), _, Jun 09 2010

Discussion

Fri Mar 30

17:31

OEIS Server: https://oeis.org/edit/global/156

#1 by N. J. A. Sloane at Sun Jul 11 03:00:00 EDT 2010

NAME

a(n) = n XOR floor(Log_2(n))+1, where XOR is bitwise XOR.

DATA

0, 1, 7, 6, 5, 4, 12, 13, 14, 15, 8, 9, 10, 11, 21, 20, 23, 22, 17, 16, 19, 18, 29, 28, 31, 30, 25, 24, 27, 26, 38, 39, 36, 37, 34, 35, 32, 33, 46, 47, 44, 45, 42, 43, 40, 41, 54, 55, 52, 53, 50, 51, 48, 49, 62, 63, 60, 61, 58, 59, 56, 57, 71, 70, 69, 68, 67, 66, 65, 64, 79, 78

OFFSET

2,3

COMMENTS

Except for 2 & 3 which are missing, is every integer present just once?

MATHEMATICA

f[n_] := BitXor[n, Floor[Log[2, n] + 1]]; t = Array[f, 75, 2];

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 09 2010

STATUS

approved