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A070410 a(n) = 7^n mod 25. 1
1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18, 1, 7, 24, 18 (list; graph; refs; listen; history; text; internal format)
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).

FORMULA

From Paolo P. Lava, Feb 25 2010: (Start)

a(n) = (1/12)*{76*(n mod 4)+43*[(n+1) mod 4]-26*[(n+2) mod 4]+7*[(n+3) mod 4]}, with n>=0.

a(n) = (25/2)-(23/4-11/4*I)*I^n-(23/4+11/4*I)*(-I)^n, with n>=0 and I=sqrt(-1). (End)

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

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

G.f.: ( -1-6*x-18*x^2 ) / ( (x-1)*(1+x^2) ). (End)

a(n) = 25 - a(n-2), n>=2. - Vincenzo Librandi, Feb 08 2011

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

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

E.g.f.: (1/2)*(25*exp(x) - 23*cos(x) - 11*sin(x)). (End)

MATHEMATICA

PowerMod[7, Range[0, 50], 25] (* G. C. Greubel, Mar 20 2016 *)

PROG

(Sage) [power_mod(7, n, 25) for n in xrange(0, 84)] # Zerinvary Lajos, Nov 27 2009

(PARI) a(n) = lift(Mod(7, 25)^n); \\ Altug Alkan, Mar 20 2016

(MAGMA) [Modexp(7, n, 25): n in [0..100]]; // Bruno Berselli, Mar 22 2016

CROSSREFS

Sequence in context: A196113 A286506 A286406 * A077035 A076602 A287132

Adjacent sequences:  A070407 A070408 A070409 * A070411 A070412 A070413

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, May 12 2002

STATUS

approved

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Last modified September 24 22:31 EDT 2017. Contains 292441 sequences.