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Search: id:A087623
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| A087623 |
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Triangle read by rows: T(m,n) is the cardinality of the set {k in [1,n-1] : gcd(k,n)=m}. |
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+0
2
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| 0, 0, 1, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 1, 4, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 6, 0, 0, 0, 0, 0, 1, 0, 4, 0, 0, 0, 0, 0, 0, 0, 2, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 1, 2, 4, 10, 0, 0, 0, 0, 0, 0
(list; table; graph; listen)
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OFFSET
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1,6
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COMMENT
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A generalization of Euler's phi function: T(1,n)=phi(n).
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EXAMPLE
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T(2,4)=1 because gcd(1,4)=1, gcd(2,4)=2, gcd(3,4)=1.
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CROSSREFS
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Cf. A000010.
Adjacent sequences: A087620 A087621 A087622 this_sequence A087624 A087625 A087626
Sequence in context: A130207 A083914 A083891 this_sequence A036274 A047753 A031123
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KEYWORD
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nonn,easy,tabl
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AUTHOR
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Michele Dondi (bik.mido(AT)tiscalinet.it), Sep 14, 2003
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