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A117672 Numbers n such that |cos(n)*cos(n+2)| < (cos(n+1))^2. 1
2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 21, 24, 25, 27, 28, 30, 31, 33, 34, 36, 37, 39, 40, 43, 46, 47, 49, 50, 52, 53, 55, 56, 58, 59, 61, 62, 65, 68, 69, 71, 72, 74, 75, 77, 78, 80, 81, 83, 84, 87, 90, 91, 93, 94, 96, 97, 99, 100, 102, 103, 105, 106, 109, 112, 113, 115 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

What is the density of the sequence? I am convinced that this sequence has the same density as A026313.

LINKS

Table of n, a(n) for n=1..68.

EXAMPLE

|cos(5)*cos(7)| < (cos(6))^2, therefore 5 is in the sequence.

MATHEMATICA

Select[Range[120], Abs[Cos[ # ]*Cos[ # + 2]] < Cos[ # + 1]^2 &]

CROSSREFS

Cf. A026313 [same definition with sin instead of cos].

Sequence in context: A052490 A332076 A248562 * A194383 A186326 A139364

Adjacent sequences:  A117669 A117670 A117671 * A117673 A117674 A117675

KEYWORD

nonn

AUTHOR

Stefan Steinerberger, Apr 12 2006

EXTENSIONS

Offset corrected by Sean A. Irvine, Sep 25 2019

STATUS

approved

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Last modified June 21 12:19 EDT 2021. Contains 345364 sequences. (Running on oeis4.)