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A246408
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Nonnegative integers k satisfying sec(k) < sec(k+1) > sec(k+2).
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3
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0, 2, 4, 6, 8, 10, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 122, 124, 126, 128
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OFFSET
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1,2
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COMMENTS
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LINKS
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MATHEMATICA
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z = 500; f[x_] := f[x] = Sec[x];
Select[Range[0, z], f[#] > f[# + 1] &] (* A246407 *)
Select[Range[0, z], f[#] < f[# + 1] > f[# + 2] &] (* A246408 *)
Select[Range[0, z], f[#] < f[# + 1] < f[# + 2] > f[# + 3] &] (* A246409 *)
Join[{0}, Position[Partition[Sec[Range[130]], 3, 1], _?(#[[1]] <#[[2]]> #[[3]]&), 1, Heads->False]//Flatten] (* Harvey P. Dale, Nov 19 2018 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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