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%I #25 Dec 18 2023 14:24:32
%S 1,2,4,8,16,32,23,5,10,20,40,39,37,33,25,9,18,36,31,21,1,2,4,8,16,32,
%T 23,5,10,20,40,39,37,33,25,9,18,36,31,21,1,2,4,8,16,32,23,5,10,20,40,
%U 39,37,33,25,9,18,36,31,21,1,2,4,8,16,32,23,5,10,20,40,39,37,33,25,9,18
%N a(n) = 2^n mod 41.
%H G. C. Greubel, <a href="/A070348/b070348.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1).
%F From _R. J. Mathar_, Feb 06 2011: (Start)
%F a(n) = a(n-1) - a(n-10) + a(n-11).
%F G.f.: (-1-x-2*x^2-4*x^3-8*x^4-16*x^5+9*x^6+18*x^7-5*x^8-10*x^9-21*x^10 ) / ( (x-1)*(x^2+1)*(x^8-x^6+x^4-x^2+1) ). (End)
%F a(n) = a(n-20). - _G. C. Greubel_, Mar 11 2016
%t PowerMod[2, Range[0, 50], 41] (* _G. C. Greubel_, Mar 11 2016 *)
%o (PARI) a(n)=lift(Mod(2,41)^n) \\ _Charles R Greathouse IV_, Mar 22 2016
%o (GAP) a:=List([0..100],n->PowerMod(2,n,41));; Print(a); # _Muniru A Asiru_, Jan 28 2019
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, May 12 2002
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