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 A087707 Number of steps for iteration of map x -> (5/3)*ceiling(x) to reach an integer > n when started at n, or -1 if no such integer is ever reached. 2
 5, 4, 1, 3, 2, 1, 2, 3, 1, 10, 4, 1, 6, 2, 1, 2, 9, 1, 3, 3, 1, 5, 2, 1, 2, 5, 1, 4, 8, 1, 3, 2, 1, 2, 3, 1, 4, 12, 1, 5, 2, 1, 2, 4, 1, 3, 3, 1, 7, 2, 1, 2, 4, 1, 5, 6, 1, 3, 2, 1, 2, 3, 1, 11, 5, 1, 4, 2, 1, 2, 6, 1, 3, 3, 1, 4, 2, 1, 2, 5, 1, 6, 4, 1, 3, 2, 1, 2, 3, 1, 6, 4, 1, 5, 2, 1, 2, 5, 1, 3 (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)[2], n=1..100)]; CROSSREFS Cf. A087704, A087705, A087706, A087708, A087709. Sequence in context: A268911 A166044 A190287 * A198352 A113011 A028875 Adjacent sequences:  A087704 A087705 A087706 * A087708 A087709 A087710 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 29 2003 STATUS approved

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Last modified June 15 00:00 EDT 2021. Contains 345041 sequences. (Running on oeis4.)