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A081482
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Consider the mapping f(a/b) = (a^3 +b^3)/(a^2+b^2). Taking a =1, b = 2 to start with and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 1/2,9/5,427/53,39001680/92569,... Sequence contains the denominators.
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1
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2, 5, 53, 92569, 1521139611842161, 1759826706496123129893760473796973076447567001, 5450165776683729363553774731808009059782198745252457060273092560160498157854877231868041524958184901475157837190479609639387791150077013
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The mapping f(a/b) = (a + b)/(a - b). Taking a = 2 b = 1 to start with and carrying out this mapping repeatedly on each new (reduced)rational number gives the periodic sequence 2/1,3/1,2/1,3/1,...
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CROSSREFS
| Cf. A081481.
Sequence in context: A081090 A071880 A071882 * A134475 A114029 A013171
Adjacent sequences: A081479 A081480 A081481 * A081483 A081484 A081485
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KEYWORD
| nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 24 2003
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EXTENSIONS
| More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
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