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a(n) = 4^n mod 10.
3

%I #25 Sep 08 2022 08:45:49

%S 1,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,

%T 6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,

%U 6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4,6,4

%N a(n) = 4^n mod 10.

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0, 1).

%F a(n) = A010879(A000302(n)). - _Michel Marcus_, Jul 23 2016

%t PowerMod[4, Range[0, 25], 10] (* _G. C. Greubel_, Jul 22 2016 *)

%o (Sage) [power_mod(4, n, 10)for n in range(0, 94)] #

%o (PARI) a(n)=lift(Mod(4,10)^n) \\ _Charles R Greathouse IV_, Mar 22 2016

%o (Magma) [Modexp(4, n, 10): n in [0..100]]; // _Vincenzo Librandi_, Jul 23 2016

%Y Cf. A000302, A010879.

%Y Last elements of rows of A008565.

%K nonn,easy

%O 0,2

%A _Zerinvary Lajos_, Nov 25 2009