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Search: id:A130043
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| A130043 |
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a(1)=1. a(n) = number of earlier terms which are coprime to the largest odd divisor of n. |
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+0
2
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| 1, 1, 2, 3, 4, 4, 6, 7, 6, 9, 10, 7, 12, 11, 8, 15, 16, 11, 18, 17, 11, 18, 22, 15, 21, 25, 16, 24, 28, 16, 30, 31, 16, 32, 25, 23, 36, 37, 25, 32, 40, 25, 42, 39, 23, 43, 46, 32, 43, 40, 34, 50, 52, 38, 39, 50, 39, 57, 58, 32, 60, 60, 39, 63, 45, 38, 66, 65, 41, 47, 70, 47, 72
(list; graph; listen)
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OFFSET
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1,3
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EXAMPLE
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The largest odd divisor of 12 is 3. So a(12) is the number of terms from among (a(1),a(2),...a(11)) which are coprime to 3, which is 7.
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MAPLE
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lod:=proc(n) if n mod 2 = 1 then n else lod(n/2) fi end: seq(lod(n), n=1..100): a[1]:=1: for n from 2 to 100 do a[n]:=0: for j from 1 to n-1 do if igcd(a[j], lod(n))=1 then a[n]:=1+a[n] else fi od: od: seq(a[n], n=1..100); # lod finds the largest odd divisor - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 22 2007
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CROSSREFS
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Cf. A130044, A000265.
Adjacent sequences: A130040 A130041 A130042 this_sequence A130044 A130045 A130046
Sequence in context: A081328 A072455 A066981 this_sequence A089266 A039696 A076332
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), May 02 2007
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), May 22 2007
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