A132380 Period 8: repeat [0, 0, 1, 1, 0, 0, -1, -1].

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

Offset: 0

Author

Paul Curtz, Nov 10 2007

Keywords

• sign
• easy
• less

Links

• Antti Karttunen, Table of n, a(n) for n = 0..8191
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,-1).

Crossrefs

Cf. A109247.

Programs

Mathematica

PadRight[{},120,{0,0,1,1,0,0,-1,-1}] (* Harvey P. Dale, Mar 17 2016 *)

PARI

a(n)=[0,0,1,1,0,0,-1,-1][n%8+1] \\ Charles R Greathouse IV, Jun 02 2011

Scheme

(define (A132380 n) (list-ref '(0 0 1 1 0 0 -1 -1) (modulo n 8))) ;; Antti Karttunen, Aug 12 2017

Formula

O.g.f.: x^2*(1+x)/(1+x^4). - R. J. Mathar, Apr 06 2008

For n > 0, a(n) = A109247(n)/-3. - Antti Karttunen, Aug 12 2017

a(n) = (1/2)*(1-(-1)^floor(n/2))*(-1)^floor(n/4). - Wesley Ivan Hurt, Aug 31 2019