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%I #6 Apr 26 2016 18:14:01
%S 1,3,5,7,9,11,12,14,16,18,20,22,24,26,28,30,32,35,37,39,41,43,45,47,
%T 49,51,53,55,56,58,60,62,64,66,68,70,72,74,76,79,81,83,85,87,89,91,93,
%U 95,97,99,100,102,104,106,108,110,112,114,116,118,120,123,125
%N Nonnegative integers k satisfying sec(k) > sec(k+1).
%C A246407, A246408, and A246409 partition the nonnegative integers.
%H Clark Kimberling, <a href="/A246407/b246407.txt">Table of n, a(n) for n = 1..1000</a>
%t z = 500; f[x_] := f[x] = Sec[x];
%t Select[Range[0, z], f[#] > f[# + 1] &] (* A246407 *)
%t Select[Range[0, z], f[#] < f[# + 1] > f[# + 2] &] (* A246408 *)
%t Select[Range[0, z], f[#] < f[# + 1] < f[# + 2] > f[# + 3] &] (* A246409 *)
%t Position[Partition[Sec[Range[150]],2,1],_?(#[[1]]>#[[2]]&),{1}, Heads-> False]//Flatten (* _Harvey P. Dale_, Apr 26 2016 *)
%Y Cf. A246408, A246409, A246404 (complement of A246407).
%K nonn,easy
%O 1,2
%A _Clark Kimberling_, Aug 25 2014