A070406 a(n) = 7^n mod 15.

1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1, 7, 4, 13, 1

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

Sequence in context: A359014 A138339 A107827 * A323997 A297938 A298549

Adjacent sequences: A070403 A070404 A070405 * A070407 A070408 A070409

Keyword

nonn,easy

Author

N. J. A. Sloane, May 12 2002

Status

approved