A330035 a(n) = sign(tan(n)).

0, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, 1, -1

Offset

0

Comments

Also sign(cot(n)) for n > 0.

Also sign(sin(2n)) = A070747(2n).

Links

Table of n, a(n) for n=0..77.

Formula

a(n) = +1 if 0 < {n/Pi} < 1/2, -1 if 1/2 < {n/Pi} < 1, where {} is the fractional part.

Mathematica

a[n_] := Sign[Tan[n]]

Prog

(PARI) a(n) = sign(tan(n))

Crossrefs

Cf. A057427 (sign), A070747 (sign(sin(n)) or sign(csc(n))), A330034 (sign(cos(n)) or sign(sec(n))), A327422 (indices of +1), A327423 (indices of -1).

Sequence in context: A070750 A011598 A324672 * A011599 A011600 A011601

Adjacent sequences: A330032 A330033 A330034 * A330036 A330037 A330038

Keyword

sign

Author

Jianing Song, Nov 27 2019

Status

approved