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A246396
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Nonnegative integers k satisfying cos(k) <= 0 and cos(k+1) <= 0.
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4
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2, 3, 8, 9, 15, 16, 21, 22, 27, 28, 33, 34, 35, 40, 41, 46, 47, 52, 53, 59, 60, 65, 66, 71, 72, 77, 78, 79, 84, 85, 90, 91, 96, 97, 103, 104, 109, 110, 115, 116, 121, 122, 123, 128, 129, 134, 135, 140, 141, 147, 148, 153, 154, 159, 160, 165, 166, 167, 172
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OFFSET
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0,1
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COMMENTS
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Conjecture: every term t has at least one neighbor which is equal to t plus or minus one. - Harvey P. Dale, Jul 11 2023
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LINKS
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MATHEMATICA
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z = 400; f[x_] := Cos[x]
Select[Range[0, z], f[#]*f[# + 1] <= 0 &] (* A062389 *)
Select[Range[0, z], f[#] >= 0 && f[# + 1] <= 0 &] (* A246393 *)
Select[Range[0, z], f[#] <= 0 && f[# + 1] >= 0 &] (* A246394 *)
Select[Range[0, z], f[#]*f[# + 1] > 0 &] (* A246046 *)
Select[Range[0, z], f[#] >= 0 && f[# + 1] >= 0 &] (* A246395 *)
Select[Range[0, z], f[#] <= 0 && f[# + 1] <= 0 &] (* A246396 *)
SequencePosition[Table[If[Cos[k]<=0, 1, 0], {k, 200}], {1, 1}][[;; , 1]] (* Harvey P. Dale, Jul 11 2023 *)
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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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