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A172448 a(1) = 1, and for each n >=2, a(n) is the smallest number such that 1/cos(a(n)) < 1/cos(k) for all k < n, so that 1/cos(a(1)) > 1/cos(a(2)) > ... > 1/cos(a(n)) > ... 2
1, 2, 8, 33, 344, 1054, 1764, 2474, 3184, 3894, 4604, 5314, 6024, 6734, 7444, 8154, 8864, 9574, 10284, 10994, 11704, 12414, 13124, 13834, 14544, 15254, 15964, 16674, 17384, 18094, 18804, 19514, 20224, 20934, 21644, 22354, 23064, 23774, 24484 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
REFERENCES
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 83, p. 29, Ellipses, Paris 2008. Also Entry 137, p. 47.
LINKS
Eric Weisstein's World of Mathematics, Pi.
EXAMPLE
1/cos(1) = 1.8508157..., 1/cos(2) = -2.402997962..., 1/cos(8) = -6.8728506...
MAPLE
a:= evalf(1/ cos(1)); for n from 2 to 10000000 do; if a > evalf(1/cos(n)) then a:= evalf(1/cos(n)); print(n); else fi ; od;
MATHEMATICA
am = 2; s = {}; Do[a = 1/Cos[n]; If[a < am, am = a; AppendTo[s, n]], {n, 1, 10^4}]; s (* Amiram Eldar, Aug 16 2019 *)
CROSSREFS
Cf. A172446.
Sequence in context: A005040 A191551 A263627 * A268601 A026577 A204090
KEYWORD
nonn
AUTHOR
Michel Lagneau, Feb 03 2010
STATUS
approved

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Last modified July 19 14:58 EDT 2024. Contains 374410 sequences. (Running on oeis4.)