This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A117672 #7 Sep 25 2019 19:18:37 %S A117672 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, %T A117672 43,46,47,49,50,52,53,55,56,58,59,61,62,65,68,69,71,72,74,75,77,78,80, %U A117672 81,83,84,87,90,91,93,94,96,97,99,100,102,103,105,106,109,112,113,115 %N A117672 Numbers n such that |cos(n)*cos(n+2)| < (cos(n+1))^2. %C A117672 What is the density of the sequence? I am convinced that this sequence has the same density as A026313. %e A117672 |cos(5)*cos(7)| < (cos(6))^2, therefore 5 is in the sequence. %t A117672 Select[Range[120], Abs[Cos[ # ]*Cos[ # + 2]] < Cos[ # + 1]^2 &] %Y A117672 Cf. A026313 [same definition with sin instead of cos]. %K A117672 nonn %O A117672 1,1 %A A117672 _Stefan Steinerberger_, Apr 12 2006 %E A117672 Offset corrected by _Sean A. Irvine_, Sep 25 2019