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A070411
a(n) = 7^n mod 26.
1
1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3, 21, 17, 15, 1, 7, 23, 5, 9, 11, 25, 19, 3
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-16*x^2+18*x^3-4*x^4-2*x^5-15*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, 80], 26] (* or *) LinearRecurrence[{1, 0, 0, 0, 0, -1, 1}, {1, 7, 23, 5, 9, 11, 25}, 81] (* Harvey P. Dale, Dec 26 2011 *)
PROG
(Sage) [power_mod(7, n, 26)for n in range(0, 81)] # Zerinvary Lajos, Nov 27 2009
(PARI) a(n) = lift(Mod(7, 26)^n); \\ Altug Alkan, Mar 20 2016
(Magma) [Modexp(7, n, 26): n in [0..100]]; // Bruno Berselli, Mar 22 2016
CROSSREFS
Sequence in context: A067959 A273216 A367002 * A340631 A367003 A167224
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved