login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Numbers k such that cos(k) < cos(k+1) < cos(k+2) < cos(k+3) > cos(k+4).
4

%I #4 Aug 23 2014 08:50:59

%S 3,10,16,22,28,35,41,47,54,60,66,72,79,85,91,98,104,110,116,123,129,

%T 135,142,148,154,160,167,173,179,185,192,198,204,211,217,223,229,236,

%U 242,248,255,261,267,273,280,286,292,299,305,311,317,324,330,336,343

%N Numbers k such that cos(k) < cos(k+1) < cos(k+2) < cos(k+3) > cos(k+4).

%C The sequences A026311, A246300, A246301, A246302 partition the nonnegative integers.

%H Clark Kimberling, <a href="/A246302/b246302.txt">Table of n, a(n) for n = 1..1000</a>

%t z = 520; f[x_] := f[x] = Cos[x]; t = Range[0, z];

%t Select[t, f[#] > f[# + 1] &] (* A026311 *)

%t Select[t, f[#] < f[# + 1] > f[# + 2] &] (* A246300 *)

%t Select[t, f[#] < f[# + 1] < f[# + 2] > f[# + 3] &] (* A246301 *)

%t Select[t, f[#] < f[# + 1] < f[# + 2] < f[# + 3] > f[# + 4] &] (* A246302 *)

%Y Cf. A026311, A246300, A246301.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Aug 22 2014