A134430 Period 4: repeat [1, -2, -2, 1].

1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2, -2, 1, 1, -2

Offset: 0

Author

Paul Curtz, Jan 31 2008

Keywords

• sign
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (1,-1,1).

Crossrefs

Cf. A014695, A134813.

Programs

Magma

&cat [[1, -2, -2, 1]^^30]; // Wesley Ivan Hurt, Jul 09 2016

Maple

seq(op([1, -2, -2, 1]), n=0..40); # Wesley Ivan Hurt, Jul 09 2016

Mathematica

PadRight[{}, 100, {1, -2, -2, 1}] (* Wesley Ivan Hurt, Jul 09 2016 *)

Formula

Binomial transform of A134813.

|a(n)| = A014695(n).

G.f.: (1-3*x+x^2) / ((1-x)*(1+x^2)). - R. J. Mathar, Jan 18 2011

From Wesley Ivan Hurt, Jul 09 2016: (Start)

a(n) = a(n-1) - a(n-2) + a(n-3) for n>2, a(n) = a(n-4) for n>3.

a(n) = (3*cos(n*Pi/2) - 3*sin(n*Pi/2) - 1)/2. (End)