A246395 Nonnegative integers k satisfying cos(k) >= 0 and cos(k+1) >= 0.

0, 5, 6, 11, 12, 13, 18, 19, 24, 25, 30, 31, 37, 38, 43, 44, 49, 50, 55, 56, 57, 62, 63, 68, 69, 74, 75, 81, 82, 87, 88, 93, 94, 99, 100, 101, 106, 107, 112, 113, 118, 119, 125, 126, 131, 132, 137, 138, 143, 144, 145, 150, 151, 156, 157, 162, 163, 169, 170

Offset: 0

Author

Clark Kimberling, Aug 24 2014

Keywords

• nonn
• easy

Comments

A246393 and A246394 partition A062389 (the nonhomogeneous Beatty sequence {floor((n-1/2)*Pi)}). Likewise, A246046, the complement of A062389, is partitioned by A246395 and A246396. (See the Mathematica program.)

Links

• Clark Kimberling, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A062389, A246393, A246046, A246394, A246396.

Programs

Mathematica

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 *)