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Search: id:A070072
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| A070072 |
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Number of distinct rectangles with integer sides <=n and square-free area. |
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+0
2
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| 1, 2, 4, 4, 7, 9, 14, 14, 14, 17, 24, 24, 32, 37, 43, 43, 54, 54, 66, 66, 74, 83, 98, 98, 98, 108, 108, 108, 125, 133, 152, 152, 165, 178, 193, 193, 216, 231, 248, 248, 274, 285, 313, 313, 313, 331, 361, 361, 361, 361, 382, 382, 414
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Eric Weisstein's World of Mathematics, square-free numbers.
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EXAMPLE
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There are seven rectangles with sides <=5 having a square-free area: 1 X 1, 1 X 2, 1 X 3, 1 X 5, 2 X 3, 2 X 5, and 3 X 5, whereas 1 X 4, 2 X 2, 2 X 4, 3 X 3, 3 X 4, 4 X 4, 4 X 5, and 5 X 5 are not square-free; therefore a(5)=7.
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CROSSREFS
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Cf. A005117, A070073.
Adjacent sequences: A070069 A070070 A070071 this_sequence A070073 A070074 A070075
Sequence in context: A132083 A102465 A139825 this_sequence A095061 A055077 A117215
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 21 2002
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