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Search: id:A007457
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| A007457 |
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# of (j,k): j+k=n, (j,n)=(k,n)=1, j,k square-free.
(Formerly M0224)
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+0
1
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| 0, 1, 2, 2, 2, 2, 4, 4, 2, 2, 4, 4, 6, 4, 4, 6, 8, 6, 6, 6, 4, 8, 8, 8, 8, 8, 8, 6, 10, 8, 10, 10, 8, 12, 8, 10, 14, 12, 10, 12, 16, 10, 18, 14, 12, 14, 16, 14, 16, 14, 10, 16, 20, 14, 12, 16, 14, 20, 18, 14, 22, 20, 16, 20
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Problem 6623, Amer. Math. Monthly, 99 (1992), 573-575.
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CROSSREFS
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Adjacent sequences: A007454 A007455 A007456 this_sequence A007458 A007459 A007460
Sequence in context: A060632 A151565 A160407 this_sequence A119802 A060369 A143979
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)
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