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Search: id:A087708
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| A087708 |
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First integer > n reached under iteration of map x -> (5/3)*ceiling(x) when started at n, or -1 if no such integer is ever reached. |
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+0
3
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| 20, 20, 5, 20, 15, 10, 20, 40, 15, 1770, 90, 20, 290, 40, 25, 45, 1770, 30, 90, 95, 35, 290, 65, 40, 70, 345, 45, 220, 1770, 50, 145, 90, 55, 95, 165, 60, 290, 17845, 65, 520, 115, 70, 120, 345, 75, 215, 220, 80, 1770, 140, 85, 145, 415, 90, 715, 1215, 95, 270, 165, 100, 170
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is conjectured that an integer is always reached.
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LINKS
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J. C. Lagarias and N. J. A. Sloane, Approximate squaring (pdf, ps), Experimental Math., 13 (2004), 113-128.
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MAPLE
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c2 := proc(x, y) x*ceil(y); end; r := 5/3; ch := proc(x) local n, y; global r; y := c2(r, x); for n from 1 to 20 do if whattype(y) = 'integer' then RETURN([x, n, y]); else y := c2(r, y); fi; od: RETURN(['NULL', 'NULL', 'NULL']); end; [seq(ch(n)[3], n=1..100)];
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CROSSREFS
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Cf. A087704, A087705, A087706, A087707, A087709.
Sequence in context: A004509 A022976 A023462 this_sequence A081245 A010859 A040381
Adjacent sequences: A087705 A087706 A087707 this_sequence A087709 A087710 A087711
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Sep 29 2003
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