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 A087708 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. 2
 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; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS It is conjectured that an integer is always reached. LINKS J. C. Lagarias and N. J. A. Sloane, Approximate squaring (pdf, ps), Experimental Math., 13 (2004), 113-128. MAPLE 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)]; CROSSREFS Cf. A087704, A087705, A087706, A087707, A087709. Sequence in context: A172164 A267058 A205545 * A220022 A217517 A332561 Adjacent sequences:  A087705 A087706 A087707 * A087709 A087710 A087711 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 29 2003 STATUS approved

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Last modified June 13 22:55 EDT 2021. Contains 345016 sequences. (Running on oeis4.)