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A246304 Numbers k such that cos(k) > cos(k+1) < cos(k+2).

%I A246304 #6 Apr 23 2015 16:24:02
%S A246304 2,8,15,21,27,34,40,46,52,59,65,71,78,84,90,96,103,109,115,122,128,
%T A246304 134,140,147,153,159,166,172,178,184,191,197,203,209,216,222,228,235,
%U A246304 241,247,253,260,266,272,279,285,291,297,304,310,316,323,329,335,341
%N A246304 Numbers k such that cos(k) > cos(k+1) < cos(k+2).
%C A246304 The sequences A246303, A246304, A246305, A246306 partition the nonnegative integers.
%H A246304 Clark Kimberling, <a href="/A246304/b246304.txt">Table of n, a(n) for n = 1..1000</a>
%t A246304 z = 500; f[x_] := f[x] = Cos[x]; t = Range[0, z];
%t A246304 Select[t, f[#] < f[# + 1] &]  (* A246303 *)
%t A246304 Select[t, f[#] > f[# + 1] < f[# + 2] &]  (* A246304 *)
%t A246304 Select[t, f[#] > f[# + 1] > f[# + 2] < f[# + 3] &]  (* A246305 *)
%t A246304 Select[t, f[#] > f[# + 1] > f[# + 2] > f[# + 3] < f[# + 4] &] (* A246306 *)
%t A246304 Flatten[Position[Partition[Cos[Range[400]],3,1],_?(#[[1]]>#[[2]] && #[[2]]< #[[3]]&),{1},Heads->False]] (* _Harvey P. Dale_, Apr 23 2015 *)
%Y A246304 Cf. A026303, A246305, A246306, A026311 (complement of A246303).
%K A246304 nonn,easy
%O A246304 1,1
%A A246304 _Clark Kimberling_, Aug 22 2014