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A070405
a(n) = 7^n mod 13.
2
1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12, 6, 3, 8, 4, 2, 1, 7, 10, 5, 9, 11, 12
OFFSET
0,2
FORMULA
From R. J. Mathar, Apr 20 2010: (Start)
a(n) = a(n-1) - a(n-6) + a(n-7).
G.f.: ( -1-6*x-3*x^2+5*x^3-4*x^4-2*x^5-2*x^6 ) / ( (x-1)*(x^2+1)*(x^4-x^2+1) ). (End)
a(n) = a(n-12). - G. C. Greubel, Mar 20 2016
MATHEMATICA
PowerMod[7, Range[0, 90], 13] (* or *) LinearRecurrence[{1, 0, 0, 0, 0, -1, 1}, {1, 7, 10, 5, 9, 11, 12}, 100] (* Harvey P. Dale, May 20 2014 *)
PROG
(Sage) [power_mod(7, n, 13) for n in range(0, 91)] # Zerinvary Lajos, Nov 03 2009
(PARI) a(n) = lift(Mod(7, 13)^n); \\ Altug Alkan, Mar 20 2016
(Magma) [Modexp(7, n, 13): n in [0..100]]; // Bruno Berselli, Mar 22 2016
CROSSREFS
Sequence in context: A122577 A180732 A266551 * A010730 A225694 A247191
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved