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Numbers k such that cos(k) < cos(k+1).
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%I #6 Aug 23 2014 08:51:31

%S 3,4,5,9,10,11,12,16,17,18,22,23,24,28,29,30,35,36,37,41,42,43,47,48,

%T 49,53,54,55,56,60,61,62,66,67,68,72,73,74,79,80,81,85,86,87,91,92,93,

%U 97,98,99,100,104,105,106,110,111,112,116,117,118,123,124

%N Numbers k such that cos(k) < cos(k+1).

%C The sequences A246303, A246304, A246305, A246306 partition the nonnegative integers.

%H Clark Kimberling, <a href="/A246303/b246303.txt">Table of n, a(n) for n = 1..4000</a>

%t z = 500; f[x_] := f[x] = Cos[x]; t = Range[0, z];

%t Select[t, f[#] < f[# + 1] &] (* A246303 *)

%t Select[t, f[#] > f[# + 1] < f[# + 2] &] (* A246304 *)

%t Select[t, f[#] > f[# + 1] > f[# + 2] < f[# + 3] &] (* A246305 *)

%t Select[t, f[#] > f[# + 1] > f[# + 2] > f[# + 3] < f[# + 4] &] (* A246306 *)

%Y Cf. A026304, A246305, A246306, A026311 (complement of A246303).

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Aug 22 2014