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A070354
a(n) = 3^n mod 16.
1
1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1, 3, 9, 11, 1
OFFSET
0,2
FORMULA
From R. J. Mathar, Apr 13 2010: (Start)
a(n) = a(n-4).
G.f.: (1 + 3*x + 9*x^2 + 11*x^3)/ ((1-x) * (1+x) * (1+x^2)). (End)
E.g.f.: 5*cosh(x) + 7*sinh(x) - 4*cos(x) - 4*sin(x). - G. C. Greubel, Mar 11 2016
MATHEMATICA
PowerMod[3, Range[0, 50], 16] (* or *) Table[Mod[3^n, 16], {n, 0, 100}] (* G. C. Greubel, Mar 11 2016 *)
PROG
(Sage) [power_mod(3, n, 16) for n in range(0, 93)] # Zerinvary Lajos, Nov 25 2009
(PARI) a(n)=lift(Mod(3, 16)^n) \\ Charles R Greathouse IV, Mar 22 2016
(Magma) [Modexp(3, n, 16): n in [0..100]]; // Bruno Berselli, Mar 23 2016
CROSSREFS
Sequence in context: A228450 A121057 A025538 * A174565 A074261 A059868
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved