A070414 a(n) = 7^n mod 30.

1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13, 1, 7, 19, 13

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 (1,-1,1). - R. J. Mathar, Apr 20 2010

Formula

From R. J. Mathar, Apr 20 2010: (Start)

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

G.f.: ( -1-6*x-13*x^2 ) / ( (x-1)*(1+x^2) ). (End)

From G. C. Greubel, Mar 20 2016: (Start)

a(n) = a(n-4).

E.g.f.: 10*exp(x) - 9*cos(x) - 3*sin(x). (End)

Mathematica

PowerMod[7, Range[0, 50], 30] (* G. C. Greubel, Mar 20 2016 *)
LinearRecurrence[{1, -1, 1}, {1, 7, 19}, 90] (* or *) PadRight[{}, 90, {1, 7, 19, 13}] (* Harvey P. Dale, Aug 09 2020 *)

Prog

(Sage) [power_mod(7, n, 30) for n in range(0, 84)] # Zerinvary Lajos, Nov 27 2009
(PARI) a(n) = lift(Mod(7, 30)^n); \\ Altug Alkan, Mar 20 2016
(Magma) [Modexp(7, n, 30): n in [0..100]]; // Bruno Berselli, Mar 22 2016

Crossrefs

Sequence in context: A362309 A226932 A245167 * A195870 A125257 A195867

Adjacent sequences: A070411 A070412 A070413 * A070415 A070416 A070417

Keyword

nonn,easy

Author

N. J. A. Sloane, May 12 2002

Status

approved