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%I #36 Dec 27 2023 07:36:24
%S 1,7,5,13,3,21,15,17,9,19,1,7,5,13,3,21,15,17,9,19,1,7,5,13,3,21,15,
%T 17,9,19,1,7,5,13,3,21,15,17,9,19,1,7,5,13,3,21,15,17,9,19,1,7,5,13,3,
%U 21,15,17,9,19,1,7,5,13,3,21,15,17,9,19,1,7,5,13,3,21,15,17,9,19,1,7,5,13
%N a(n) = 7^n mod 22.
%H G. C. Greubel, <a href="/A070408/b070408.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,-1,1).
%F From _R. J. Mathar_, Apr 20 2010: (Start)
%F a(n) = a(n-1) - a(n-5) + a(n-6).
%F G.f.: ( -1-6*x+2*x^2-8*x^3+10*x^4-19*x^5 ) / ( (x-1)*(1+x)*(x^4-x^3+x^2-x+1) ). (End)
%F a(n) = a(n-10). - _G. C. Greubel_, Mar 20 2016
%t PowerMod[7, Range[0, 50], 22] (* _G. C. Greubel_, Mar 20 2016 *)
%o (Sage) [power_mod(7,n,22) for n in range(0,84)] # _Zerinvary Lajos_, Nov 27 2009
%o (PARI) a(n) = lift(Mod(7, 22)^n); \\ _Altug Alkan_, Mar 20 2016
%o (Magma) [Modexp(7, n, 22): n in [0..100]]; // _Bruno Berselli_, Mar 22 2016
%K nonn
%O 0,2
%A _N. J. A. Sloane_, May 12 2002
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