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A109671
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a(1)=1; thereafter, a(2n)=a(n), a(2n+1) is the smallest positive number such that |a(2n+1)-a(2n-1)|=a(n).
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9
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1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 3, 6, 1, 5, 2, 3, 1, 2, 1, 1, 2, 3, 3, 6, 3, 3, 6, 9, 1, 8, 5, 3, 2, 1, 3, 4, 1, 3, 2, 1, 1, 2, 1, 1, 2, 3, 3, 6, 3, 3, 6, 9, 3, 6, 3, 3, 6, 9, 9, 18, 1, 17, 8, 9, 5, 4, 3, 1, 2, 3, 1, 2, 3, 5, 4, 1, 1, 2, 3, 5, 2, 3, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 3, 6, 3, 3, 6, 9, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| A variant of the semi-Fibonacci numbers A030067.
Self-describing: the sequence of the absolute differences between odd-indexed terms is the sequence itself.
It appears that the record values form sequence A038754 and occur at indices of the form 2^k-1. - N. J. A. Sloane, Mat 02 2010
Does the sequence contain every positive integer (cf. A169741)?
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LINKS
| N. J. A. Sloane, Table of n, a(n) for n = 1..10000
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MAPLE
| f:=proc(n) option remember; local t1;
if n = 1 then RETURN(1);
elif n mod 2 = 0 then RETURN(f(n/2));
else t1:= f(n-2)-f((n-1)/2);
if t1 > 0 then RETURN(t1) else RETURN(f(n-2)+f((n-1)/2)); fi; fi; end;
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CROSSREFS
| A variant of A030067. Cf. A169741-A169745.
Sequence in context: A184219 A180262 A161789 * A141289 A177219 A140191
Adjacent sequences: A109668 A109669 A109670 * A109672 A109673 A109674
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KEYWORD
| nonn,nice
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AUTHOR
| Eric Angelini (Eric.Angelini(AT)kntv.be), Apr 30 2010
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EXTENSIONS
| Edited by N. J. A. Sloane, May 02 2010
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