A070388 a(n) = 5^n mod 42.

1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17, 1, 5, 25, 41, 37, 17

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 (2, -2, 1).

Formula

From R. J. Mathar, Dec 16 2009: (Start)

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

G.f.: (1+3*x+17*x^2)/((1-x)*(x^2-x+1)). (End)

a(n) = (1/15)*{61*(n mod 6)+71*[(n+1) mod 6]+31*[(n+2) mod 6]-19*[(n+3) mod 6]-29*[(n+4) mod 6]+11*[(n+5) mod 6]}, with n>=0. - Paolo P. Lava, Apr 16 2010

a(n) = a(n-1) - a(n-2) + 21, n>=2. - R. J. Mathar, Nov 07 2015

a(n) = a(n-6). - G. C. Greubel, Mar 16 2016

Mathematica

PowerMod[5, Range[0, 50], 42] (* G. C. Greubel, Mar 16 2016 *)

Prog

(Sage) [power_mod(5, n, 42) for n in range(0, 78)] # Zerinvary Lajos, Nov 26 2009
(PARI) a(n) = lift(Mod(5, 42)^n); \\ Altug Alkan, Mar 16 2016

Crossrefs

Sequence in context: A098993 A099799 A093534 * A250314 A293571 A294256

Adjacent sequences: A070385 A070386 A070387 * A070389 A070390 A070391

Keyword

nonn,easy

Author

N. J. A. Sloane, May 12 2002

Status

approved