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A119655
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a(0) = a(1) = 0. a(n) = number of earlier terms of the sequence which are not coprime to n.
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1
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0, 0, 2, 2, 4, 2, 6, 2, 8, 3, 9, 2, 12, 2, 12, 7, 13, 2, 16, 2, 16, 8, 18, 2, 22, 2, 23, 8, 24, 2, 27, 2, 26, 11, 27, 3, 32, 2, 29, 14, 30, 2, 38, 2, 35, 14, 36, 2, 42, 7, 39, 16, 41, 2, 46, 6, 45, 19, 43, 2, 51, 2, 44, 24, 46, 8, 57, 2, 50, 24, 55, 2, 61, 2, 53, 25, 55, 13, 64, 2, 60
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OFFSET
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0,3
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LINKS
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Diana Mecum, Table of n, a(n) for n = 1..1199 [From Diana Mecum (diana.mecum(AT)gmail.com), Aug 15 2008]
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EXAMPLE
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Among the first 20 terms of the sequence there are 8 terms which are not coprime to 21 - a(0)=0, a(1)=0, a(6)=6, a(9)=3, a(10)=9, a(12)=12, a(14)=12 and a(15)=7. So a(21) = 8.
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MATHEMATICA
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a = {0, 0}; Do[AppendTo[a, Length[Select[a, GCD[Length[a], # ] > 1 &]]], {70}]; a - Stefan Steinerberger, Oct 16 2007
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CROSSREFS
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Sequence in context: A137849 A118982 A129457 * A083260 A046523 A071364
Adjacent sequences: A119652 A119653 A119654 * A119656 A119657 A119658
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Jul 28 2006
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EXTENSIONS
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More terms from Stefan Steinerberger, Oct 16 2007
Terms a(72) through a(1200) from Diana Mecum (diana.mecum(AT)gmail.com), Aug 15 2008
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STATUS
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approved
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