OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,1).
FORMULA
From R. J. Mathar, Apr 20 2010: (Start)
a(n) = a(n-4).
G.f.: ( -1 - 7*x - 4*x^2 - 13*x^3 ) / ( (x-1)*(1+x)*(1+x^2) ). (End)
E.g.f.: (1/2)*(5*cosh(x) + 20*sinh(x) - 3*cos(x) - 6*sin(x)). - G. C. Greubel, Mar 20 2016
MATHEMATICA
PowerMod[7, Range[0, 50], 15] (* G. C. Greubel, Mar 20 2016 *)
LinearRecurrence[{0, 0, 0, 1}, {1, 7, 4, 13}, 100] (* or *) PadRight[{}, 100, {1, 7, 4, 13}] (* Harvey P. Dale, Oct 13 2018 *)
PROG
(Sage) [power_mod(7, n, 15) for n in range(0, 93)] # Zerinvary Lajos, Nov 27 2009
(PARI) a(n) = lift(Mod(7, 15)^n); \\ Altug Alkan, Mar 20 2016
(Magma) [Modexp(7, n, 15): n in [0..100]]; // Bruno Berselli, Mar 22 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved