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a(n) = n^4 mod 25.
0

%I #15 Dec 18 2023 17:23:08

%S 0,1,16,6,6,0,21,1,21,11,0,16,11,11,16,0,11,21,1,21,0,6,6,16,1,0,1,16,

%T 6,6,0,21,1,21,11,0,16,11,11,16,0,11,21,1,21,0,6,6,16,1,0,1,16,6,6,0,

%U 21,1,21,11,0,16,11,11,16,0,11,21,1,21,0,6,6,16,1,0,1,16,6,6,0,21,1,21

%N a(n) = n^4 mod 25.

%C Periodic with period length equal to 25. - _Harvey P. Dale_, May 11 2020

%H <a href="/index/Rec#order_25">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

%t PowerMod[Range[0,90],4,25] (* or *) PadRight[{},120,{0,1,16,6,6,0,21,1,21,11,0,16,11,11,16,0,11,21,1,21,0,6,6,16,1}] (* _Harvey P. Dale_, May 11 2020 *)

%o (Sage) [power_mod(n,4,25)for n in range(0, 84)] # - _Zerinvary Lajos_, Oct 31 2009

%o (PARI) a(n)=n^4%25 \\ _Charles R Greathouse IV_, Apr 06 2016

%K nonn,easy

%O 0,3

%A _N. J. A. Sloane_, May 13 2002