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Search: id:A118319
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| A118319 |
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a(n) = (highest power of 2 dividing n)th integer among those positive integers not occurring in {a(1),a(2),a(3),..a(n-1)}. |
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+0
2
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| 1, 3, 2, 7, 4, 6, 5, 15, 8, 10, 9, 14, 11, 13, 12, 31, 16, 18, 17, 22, 19, 21, 20, 30, 23, 25, 24, 29, 26, 28, 27, 63, 32, 34, 33, 38, 35, 37, 36, 46, 39, 41, 40, 45, 42, 44, 43, 62, 47, 49, 48, 53, 50, 52, 51, 61, 54, 56, 55, 60, 57, 59, 58, 127, 64, 66, 65, 70, 67, 69, 68, 78
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Sequence is a permutation of the positive integers. a(2n-1) is the smallest positive integer not occurring earlier in the sequence.
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EXAMPLE
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4 is the highest power of 2 dividing 12. Those positive integers not occurring among the first 11 terms of the sequence form the sequence 11, 12, 13, 14, 16,... Now 14 is the 4th of these integers, so a(12) = 14.
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MAPLE
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A007814 := proc(n) local a, nshf ; a := 0 ; nshf := n ; while nshf mod 2 = 0 do nshf := nshf/2 ; a := a+1 ; od; RETURN(a) ; end: A118319 := proc(nmin) local a, anxt, i, n ; a := [1] ; while nops(a) < nmin do n := nops(a)+1 ; i := 2^A007814(n); anxt := 0 ; while i > 0 do anxt := anxt+1 ; while anxt in a do anxt := anxt+1 ; od ; i := i-1; od ; a := [op(a), anxt] ; od; a ; end: A118319(80) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 06 2007
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CROSSREFS
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Cf. A118320, A006519.
Sequence in context: A135542 A130109 A108644 this_sequence A085168 A113658 A059029
Adjacent sequences: A118316 A118317 A118318 this_sequence A118320 A118321 A118322
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KEYWORD
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easy,nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Apr 23 2006
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 06 2007
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