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Search: id:A081478
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| A081478 |
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Consider the mapping f(a/b) = (a - b)/(ab). Taking a = 2 b = 1 to start with, and carrying out this mapping repeatedly on each new (reduced) rational number gives the following sequence 2/1,1/2,-1/2,-3/-2,-1/6,... Sequence contains the denominators. |
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2
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| 1, 2, 2, -2, 6, -6, 42, -42, 1806, -1806, 3263442, -3263442, 10650056950806, -10650056950806, 113423713055421844361000442, -113423713055421844361000442, 12864938683278671740537145998360961546653259485195806
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OFFSET
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1,2
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COMMENT
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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
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A003687 gives the numerators.
Cf. A007018.
Sequence in context: A032558 A139552 A064943 this_sequence A105341 A121698 A087482
Adjacent sequences: A081475 A081476 A081477 this_sequence A081479 A081480 A081481
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KEYWORD
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sign,frac
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 24 2003
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EXTENSIONS
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More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003
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