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A112792
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Array where a(1,1)=1 and m-th term of n-th row is number of terms of (n-1)th row which are coprime to the m-th positive integer coprime to n and <=n.
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2
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1, 1, 1, 1, 2, 2, 2, 0, 2, 0, 4, 2, 2, 0, 2, 0, 2, 0, 6, 3, 3, 3, 4, 3, 3, 4, 4, 3, 6, 3, 6, 3, 4, 2, 0, 2, 4, 0, 4, 2, 0, 2, 10, 7, 7, 7, 4, 3, 4, 3, 3, 3, 1, 3, 4, 3, 4, 3, 12, 5, 12, 5, 12, 12, 6, 2, 2, 6, 2, 6, 6, 2, 8, 4, 8, 8, 4, 8, 8, 4, 8, 0, 8, 0, 8, 0, 8, 0, 8, 0, 8, 0, 8, 0, 8, 0, 16, 8
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OFFSET
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1,5
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COMMENTS
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Number of terms in row n is A000010(n).
For the purpose of this sequence, GCD(0,n)=n. Since being "coprime" means that the greatest divisor common to two numbers is 1, 0 is only coprime to 1. [From Diana L. Mecum, Aug 07 2008]
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LINKS
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EXAMPLE
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The irregular array's 5th row is [2,0,2,0]. The integers coprime to 6 and <= 6 are 1 and 5. In the 5th row there are 4 terms coprime to 1 and there are 2 terms coprime to 5. So the 6th row of the array is [4,2].
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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