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A070430
a(n) = n^2 mod 5.
11
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
0,3
COMMENTS
Equivalently n^6 mod 5. - 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)
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 *)
PROG
(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
(PARI) a(n)=n^2%5 \\ Charles R Greathouse IV, Sep 28 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved