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A060837
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List the positive rationals in the canonical order as in A038566 and apply the Sagher map to turn them into integers.
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2
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1, 2, 4, 3, 9, 8, 12, 18, 16, 5, 25, 6, 20, 72, 48, 50, 36, 7, 45, 75, 49, 32, 28, 80, 200, 98, 64, 27, 63, 147, 81, 10, 108, 288, 112, 150, 180, 392, 192, 162, 100, 11, 175, 245, 121, 24, 44, 90, 432, 800, 252, 294, 320, 648, 300, 242, 144, 13, 99, 675, 405, 363, 169, 14
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The Sagher map sends Product p_i^e_i / Product q_i^f_i (p_i and q_i being distinct primes) to Product p_i^(2e_i) * Product q_i^(2f_i-1). This map is multiplicative.
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REFERENCES
| Y. Sagher, Counting the rationals, Amer. Math. Monthly, 96 (1989), p. 823.
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EXAMPLE
| The first few rationals and their images are 1/1 -> 1, 1/2 -> 2, 2/1 -> 4, 1/3 -> 3, 3/1 -> 9, 1/4 -> 8, ...
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CROSSREFS
| Cf. A038566, A071970.
Sequence in context: A111390 A129596 A157182 * A019600 A096901 A100781
Adjacent sequences: A060834 A060835 A060836 * A060838 A060839 A060840
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KEYWORD
| nonn,nice,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jun 19 2002
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EXTENSIONS
| More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jan 12 2003
Corrected by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Sep 02 2009
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