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 A068119 Number of steps to reach an integer starting with n + 1/4 and iterating the map x -> x*ceiling(x). 12
 3, 3, 1, 3, 2, 2, 1, 7, 4, 4, 1, 2, 2, 4, 1, 6, 3, 5, 1, 5, 2, 2, 1, 4, 6, 3, 1, 2, 2, 3, 1, 7, 3, 4, 1, 3, 2, 2, 1, 7, 4, 7, 1, 2, 2, 5, 1, 3, 3, 10, 1, 4, 2, 2, 1, 3, 5, 11, 1, 2, 2, 3, 1, 5, 3, 3, 1, 3, 2, 2, 1, 4, 4, 6, 1, 2, 2, 4, 1, 4, 3, 6, 1, 6, 2, 2, 1, 6, 7, 3, 1, 2, 2, 3, 1, 4, 3, 5, 1, 3, 2, 2, 1, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If the initial value is n + 1/2 we get A001511. S(n)=sum(k=1, n, a(k)) seems to be asymptotic to 3*n. S(n)=3n for in A074069. The sign of 3n-S(n) seems to change often: 3n-S(n) gives A074077. Is 3n-S(n) bounded? - Benoit Cloitre, Sep 05 2002 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 J. C. Lagarias and N. J. A. Sloane, Approximate squaring (pdf, ps), Experimental Math., 13 (2004), 113-128. FORMULA a(n) = 1 if n == 3 (mod 4); a(n) = 2 if n == 5, 6, 12, 13 (mod 16); a(n) = 3 if n == 1, 2, 4, 17, 26, 30, 33, 36, 48, 49, 56, 62 (mod 64);... MATHEMATICA ce[n_] := Length[NestWhileList[#*Ceiling[#] &, n + 1/4, ! IntegerQ[#] &]] - 1; ce /@ Range[104] (* Jayanta Basu, Jul 29 2013 *) PROG (PARI) a(n)=if(n<0, 0, s=n+1/4; c=0; while(frac(s)>0, s=s*ceil(s); c++); c) (Haskell) import Data.Ratio ((%), denominator) a068119 n = fst \$ until ((== 1) . denominator . snd) (\(i, x) -> (i + 1, f x)) (0, fromInteger n + 1%4) where f x = x * fromIntegral (ceiling x) -- Reinhard Zumkeller, May 26 2013 CROSSREFS Cf. A073524, A074069, A074077 Sequence in context: A055177 A030778 A324078 * A039992 A101988 A200606 Adjacent sequences: A068116 A068117 A068118 * A068120 A068121 A068122 KEYWORD nonn AUTHOR Benoit Cloitre, Aug 30 2002 EXTENSIONS Corrected by Diego Torres (torresvillarroel(AT)hotmail.com), Aug 31 2002 STATUS approved

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Last modified September 8 00:04 EDT 2024. Contains 375749 sequences. (Running on oeis4.)