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Search: id:A085058
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| 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 6, 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 7, 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 6, 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 8, 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 6, 2, 3, 2, 4, 2, 3, 2, 5, 2, 3, 2, 4, 2, 3, 2, 7, 2, 3, 2, 4, 2, 3, 2, 5, 2
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Number of divisors of 2n of the form 2^k. - Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jul 25 2007
Number of steps for iteration of map x -> (3/2)*ceiling(x) to reach an integer when started at 2*n+1.
Also number of steps for iteration of map x -> (3/2)*floor(x) to reach an integer when started at 2*n+3. - Benoit Cloitre, Sep 27 2003
The first time that a(n) = e+1 is when n is of the form 2^e - 1. - Robert G. Wilson v Sep 28 2003. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 29 2003
a(n) = A007814(3^(n+1) - (-1)^(n+1)) = A007814(A105723(n+1)). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 18 2005
Let 2^k(n) = largest power of 2 dividing tangent number T(n). Then a(n) = 2*n-k(n). - Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), Dec 23 2006
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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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FORMULA
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a(n) = A001511(n) + 1 = A001511(2n). - Ray Chandler, Jul 29 2007
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MAPLE
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f := x->(3/2)*ceil(x); g := proc(n) local t1, c; global f; t1 := f(n); c := 1; while not type(t1, 'integer') do c := c+1; t1 := f(t1); od; RETURN([c, t1]); end;
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MATHEMATICA
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g = 3 Ceiling[ # ]/2 &; f[n_?OddQ] := Length @ NestWhileList[ g, g[n], !IntegerQ[ # ] & ]; Table[ f[n], {n, 1, 210, 2}]
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PROGRAM
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(PARI) A085058(n)=if(n<0, 0, c=2*n+7/2; x=0; while(frac(c)>0, c=3/2*floor(c); x++); x) (from Benoit Cloitre)
(PARI) A085058(n)=if(n<0, 0, c=(2*n+1)*3/2; x=1; while(frac(c)>0, c=3/2*ceil(c); x++); x) (from Benoit Cloitre)
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CROSSREFS
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Cf. A001511, A085060.
Sequence in context: A066482 A089080 A123725 this_sequence A080771 A025477 A080189
Adjacent sequences: A085055 A085056 A085057 this_sequence A085059 A085060 A085061
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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), Aug 11 2003
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