A133186 Period 4: repeat [1, 2, 1, -4].

1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4, 1, 2, 1, -4

Offset

0,2

Links

Table of n, a(n) for n=0..75.

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

Formula

G.f.: 1/(1+x)+3x/(1+x^2). a(n) = (-1)^n+3*A056594(n-1). [R. J. Mathar, Oct 30 2008]

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

a(n) + a(n-1) + a(n-2) + a(n-3) = 0 for n>2, a(n) = a(n-4) for n>3.

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

Maple

seq(op([1, 2, 1, -4]), n=0..40); # Wesley Ivan Hurt, Jul 09 2016

Mathematica

PadRight[{}, 100, {1, 2, 1, -4}] (* Wesley Ivan Hurt, Jul 09 2016 *)

Prog

(Magma) &cat [[1, 2, 1, -4]^^30]; // Wesley Ivan Hurt, Jul 09 2016

Crossrefs

Cf. A056594, A109008.

Sequence in context: A324892 A059150 A087230 * A084236 A068057 A335852

Adjacent sequences: A133183 A133184 A133185 * A133187 A133188 A133189

Keyword

sign,easy

Author

Paul Curtz, Oct 07 2007

Status

approved