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Final 2 digits of 4^n.
1

%I #21 Sep 08 2022 08:44:29

%S 1,4,16,64,56,24,96,84,36,44,76,4,16,64,56,24,96,84,36,44,76,4,16,64,

%T 56,24,96,84,36,44,76,4,16,64,56,24,96,84,36,44,76,4,16,64,56,24,96,

%U 84,36,44,76,4,16,64,56,24,96

%N Final 2 digits of 4^n.

%C The period is 10: for n > 0, a(n) = a(n + 10).

%H Vincenzo Librandi, <a href="/A001264/b001264.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Fi#final">Index entries for sequences related to final digits of numbers</a>

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,-1,1).

%p seq(4^n mod 10^2,n=0..60); # _Martin Renner_, Jan 25 2017

%t PowerMod[4, Range[0, 60], 100] (* _Vincenzo Librandi_, Aug 15 2016 *)

%o (Magma) [Modexp(4, n, 100): n in [0..110]]; // _Vincenzo Librandi_, Aug 15 2016

%o (PARI) a(n)=lift(Mod(4,100)^n) \\ _Charles R Greathouse IV_, Jan 25 2017

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_