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A128330
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a(1)=1. a(n) = number of positive numbers <= n that are coprime to the product of the first n-1 terms of this sequence.
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1
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1, 2, 2, 2, 3, 2, 3, 3, 3, 3, 4, 4, 5, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 6, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 11, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 13, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 16, 16, 17, 16, 16, 16, 17
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..83.
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EXAMPLE
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The first 6 terms of the sequence are 1,2,2,2,3,2,3. The number of positive integers <= 7 that are coprime to 1, 2 and 3 is three, these integers being 1, 5 and 7. So a(7) = 3.
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MAPLE
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a[1]:=1: for n from 2 to 105 do a[n]:=0: for j from 1 to n do if igcd(j, product(a[i], i=1..n-1))=1 then a[n]:=a[n]+1 else fi od: od: seq(a[n], n=1..105); # Emeric Deutsch, May 22 2007
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CROSSREFS
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Sequence in context: A263799 A299230 A182576 * A133801 A181630 A112310
Adjacent sequences: A128327 A128328 A128329 * A128331 A128332 A128333
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet, May 04 2007
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EXTENSIONS
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More terms from Emeric Deutsch, May 22 2007
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STATUS
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approved
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