A070430 a(n) = n^2 mod 5.

0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0, 1, 4, 4, 1, 0

Offset: 0

Author

N. J. A. Sloane, May 12 2002

Keywords

• nonn
• easy

Comments

Equivalently n^6 mod 5. - Zerinvary Lajos, Nov 06 2009

Links

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

Crossrefs

Cf. A053879, A070431, A070432.

Programs

Mathematica

Table[Mod[n^2,5],{n,0,200}] (* Vladimir Joseph Stephan Orlovsky, Apr 21 2011 *)
PowerMod[Range[0, 200], 2, 5] (* G. C. Greubel, Mar 22 2016 *)

PARI

a(n)=n^2%5 \\ Charles R Greathouse IV, Sep 28 2015

Sage

[power_mod(n,2,5)for n in range(0, 101)] # Zerinvary Lajos, Nov 06 2009

Sage

[power_mod(n,6,5)for n in range(0, 101)] # Zerinvary Lajos, Nov 06 2009

Formula

From R. J. Mathar, Apr 20 2010: (Start)

a(n) = a(n-5).

G.f.: -x*(1+x)*(x^2+3*x+1) / ( (x-1)*(1+x+x^2+x^3+x^4) ). (End)