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 A270826 Maximum number of iterations needed in the Euclid algorithm for gcd(x,y) in [1..n]. 0
 0, 2, 2, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES R. Crandall and C. Pomerance, Prime Numbers: A Computational Perspective, Springer, NY, 2001; see Theorem 2.1.3 p. 84. LINKS FORMULA a(n) = ceiling(log(n*sqrt(5))/log((sqrt(5)+1)/2)) - 2. MATHEMATICA With[{s = Sqrt@ 5}, Table[Ceiling[Log[n s]/Log[(s + 1)/2]] - 2, {n, 89}]] (* Michael De Vlieger, Mar 24 2016 *) PROG (PARI) a(n) = ceil(log(n*sqrt(5))/log((sqrt(5)+1)/2)) - 2; CROSSREFS Sequence in context: A326539 A297995 A081228 * A003002 A087180 A029121 Adjacent sequences:  A270823 A270824 A270825 * A270827 A270828 A270829 KEYWORD nonn AUTHOR Michel Marcus, Mar 23 2016 STATUS approved

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Last modified December 9 22:27 EST 2019. Contains 329880 sequences. (Running on oeis4.)