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Search: id:A082008
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| 1, 2, 3, 4, 7, 10, 13, 5, 6, 8, 9, 11, 12, 14, 15, 16, 31, 46, 61, 76, 91, 106, 121, 136, 151, 166, 181, 196, 211, 226, 241, 17, 18, 32, 33, 47, 48, 62, 63, 77, 78, 92, 93, 107, 108, 122, 123, 137, 138, 152, 153, 167, 168, 182, 183, 197, 198
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Contribution from Steve Witham (sw(AT)tiac.net), Oct 13 2009: (Start)
Starting the sequence (and its index) at 1 (as in A082008) instead of 0 (as in A082007) seems more natural. This was conceived as a way to arrange a heapsort in memory to improve locality of reference. The classic Williams/Floyd heapsort also works a little more naturally when the origin is 1.
This sequence is a permutation of the integers >= 1. (End)
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LINKS
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Steve Witham, Clumpy Heapsort
Steve Witham, Clumpy Heapsort. [From Steve Witham (sw(AT)tiac.net), Oct 13 2009]
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FORMULA
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May be defined recursively by:
def A082008( n ):
if n == 1: return 1
y = 2 ** int( log( n, 2 ) )
yc = 2 ** 2 ** int( log( log( y, 2 ), 2 ) )
yr = y / yc
return (yc-1) * int( (n-y) / yr + 1 ) + A082008( yr + n % yr ) (from Steve Witham, Oct 14 2009)
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PROGRAM
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Contribution from Steve Witham (sw(AT)tiac.net), Oct 13 2009: (Start)
(Python) \D def A082008( n ):
..if n == 1: return 1
..
..y = 2 ** int( log( n, 2 ) )
..yc = 2 ** 2 ** int( log( log( y, 2 ), 2 ) )
..yr = y / yc
..return (yc-1) * int( (n-y) / yr + 1 ) + A082008( yr + n % yr )
(End)
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CROSSREFS
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Sequence in context: A104519 A117220 A118426 this_sequence A105330 A097545 A073627
Adjacent sequences: A082005 A082006 A082007 this_sequence A082009 A082010 A082011
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KEYWORD
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nonn,tabf
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Oct 06 2009, based on a posting by Steve Witham (sw(AT)tiac.net) to the Math Fun Mailing List, Sep 30 2009
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EXTENSIONS
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The origin is 1 Steve Witham (sw(AT)tiac.net), Oct 13 2009
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