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

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

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

Programs

Magma

&cat [[0,4]^^50]; // Bruno Berselli, Dec 10 2015

Mathematica

PadRight[{},120,{0,4}] (* Harvey P. Dale, Feb 11 2025 *)

PARI

a(n)=n%2*4 \\ Charles R Greathouse IV, Jul 23 2016

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