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Search: id:A089059
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| A089059 |
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Numbers x such that xy/(x+y) is an integer and the hypotenuse of the right triangle with legs x and y is an integer. |
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+0
1
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| 21, 42, 63, 84, 85, 105, 126, 147, 168, 170, 184, 189, 210, 217, 231, 252, 255, 273, 294, 315, 336, 340, 357, 368, 378, 399, 420, 425, 434, 441, 441, 462, 483
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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These numbers are almost always divisible by 7. 85 in the example is an exception and so is 184.
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EXAMPLE
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x=85,y=204, 85^2+204^2 = 221^2
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PROGRAM
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(PARI) xydivxpy2(n) = { for(x=1, n, for(y=x, n, h=x*y/(x+y); if(h==floor(h), z = sqrt (x^2+y^2); if(z==floor(z), print1(x", ") ) ) ) ) }
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CROSSREFS
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Sequence in context: A120772 A040420 A037978 this_sequence A114384 A008603 A086794
Adjacent sequences: A089056 A089057 A089058 this_sequence A089060 A089061 A089062
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Dec 02 2003, corrected Nov 23 2006
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