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A070102
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Number of obtuse integer triangles with perimeter n and relatively prime side lengths.
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7
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0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 2, 0, 2, 1, 3, 2, 3, 2, 5, 3, 6, 2, 8, 5, 9, 5, 9, 6, 11, 6, 14, 9, 14, 9, 17, 11, 19, 12, 19, 15, 23, 13, 27, 18, 26, 16, 32, 20, 33, 21, 34, 26, 40, 23, 42, 29, 42, 29, 50, 32, 53, 35, 48, 41, 58, 37, 64, 45, 60, 42, 71
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,11
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COMMENTS
| a(n) = A051493(n) - A070094(n) - A070109(n).
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LINKS
| R. Zumkeller, Integer-sided triangles
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EXAMPLE
| For n=9 there are A005044(9)=3 integer triangles: [1,4,4], [2,3,4] and [3,3,3]; only one of them is obtuse: 2^2+3^2<16=4^2 and GCD(2,3,4)=1, therefore a(9)=1.
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CROSSREFS
| Cf. A070080, A070081, A070082, A070101, A051493, A070104, A070107, A070084, A070128.
Sequence in context: A114325 A101048 A204389 * A029182 A035373 A197317
Adjacent sequences: A070099 A070100 A070101 * A070103 A070104 A070105
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 05 2002
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