A168400 3^n mod 15.

1, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3, 9, 12, 6, 3

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, -1, 1).

Formula

From R. J. Mathar, Apr 13 2010: (Start)

a(n) = a(n-1) -a(n-2) +a(n-3), n>3.

G.f.: (1 + 2*x + 7*x^2 + 5*x^3)/((1-x)*(1+x^2)). (End)

Mathematica

Table[Mod[3^n, 15], {n, 0, 50}] (* G. C. Greubel, Jul 21 2016 *)

Prog

(Sage) [power_mod(3, n, 15) for n in range(0, 90)]
(PARI) a(n)=lift(Mod(3, 15)^n) \\ Charles R Greathouse IV, Mar 22 2016
(Magma) [Modexp(3, n, 15): n in [0..110]]; // Vincenzo Librandi, Jul 21 2016

Crossrefs

Sequence in context: A069871 A061957 A136984 * A310318 A310319 A073105

Adjacent sequences: A168397 A168398 A168399 * A168401 A168402 A168403

Keyword

nonn,easy

Author

Zerinvary Lajos, Nov 25 2009

Status

approved