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A063510
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a(1) = 1, a(n) = a(floor(square root(n)) + 1 for n > 1.
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1
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1, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(n) = A010096(n) until n = 255, but 5 = a(256) <> A010096(256) = 4
The least k such that a(k)=n for n>=2 is given by k=2^(2^(n-2)) so the closed form for a(n) follows. - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 28 2005
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FORMULA
| a(1)=1 for n>=2 a(n)=floor(log(4*log(n)/log(2))/log(2)) - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 28 2005
Equivalently, a(n) = 2 + floor(lg lg n) for n > 1. [Charles R Greathouse IV, Dec 19 2011]
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PROG
| (PARI) a(n)=if(n<2, 1, floor(log(4*log(n)/log(2))/log(2)))
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CROSSREFS
| Cf. A010096.
Sequence in context: A165024 A157639 A010096 * A156878 A140474 A091195
Adjacent sequences: A063507 A063508 A063509 * A063511 A063512 A063513
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KEYWORD
| easy,nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 30 2001
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