OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1, 0, -1, 1).
FORMULA
From R. J. Mathar, Apr 13 2010: (Start)
a(n) = a(n-1) - a(n-3) + a(n-4).
G.f.: (1 + 3*x - x^2 + 10*x^3)/ ((1-x) * (1+x) * (x^2-x+1)). (End)
From Wesley Ivan Hurt, Sep 08 2022: (Start)
a(n) = (39-13*(-1)^n-20*cos(n*Pi/3)-12*sqrt(3)*sin(n*Pi/3))/6.
a(n) = a(n-6) for n >= 6. (End)
MATHEMATICA
PowerMod[4, Range[0, 100], 13] (* or *) PadRight[{}, 100, {1, 4, 3, 12, 9, 10}] (* Harvey P. Dale, Mar 15 2015 *)
PROG
(Sage) [power_mod(4, n, 13)for n in range(0, 90)] #
(PARI) a(n)=lift(Mod(4, 13)^n) \\ Charles R Greathouse IV, Mar 22 2016
(Magma) [Modexp(4, n, 13): n in [0..100]]; /* or */ &cat[[1, 4, 3, 12, 9, 10]^^20]; // Vincenzo Librandi, Jul 23 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Zerinvary Lajos, Nov 25 2009
STATUS
approved