A010675 Period 2: repeat (0,4).

0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0, 4, 0

Offset

0,2

Links

Table of n, a(n) for n=0..80.

Index entries for linear recurrences with constant coefficients, signature (0,1).

Formula

a(n) = 2*(1-(-1)^n); a(n) = 4*(n mod 2) - Paolo P. Lava, Oct 20 2006

O.g.f.: -2/(1+x)-2/(x-1). - R. J. Mathar, Feb 19 2008

a(n) = 4*(1+floor((n+1)/2)-ceiling((n+1)/2)). - Wesley Ivan Hurt, May 21 2013

a(n) = 4*cos( Pi*(n+1)/2 )^2. - Wesley Ivan Hurt, May 21 2013

Prog

(Magma) &cat [[0, 4]^^50]; // Bruno Berselli, Dec 10 2015
(PARI) a(n)=n%2*4 \\ Charles R Greathouse IV, Jul 23 2016

Crossrefs

Sequence in context: A230031 A019920 A246130 * A035673 A035638 A347156

Adjacent sequences: A010672 A010673 A010674 * A010676 A010677 A010678

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved