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A070483 a(n) = n^3 mod 21. 1

%I #18 Dec 18 2023 14:49:04

%S 0,1,8,6,1,20,6,7,8,15,13,8,6,13,14,15,1,20,15,13,20,0,1,8,6,1,20,6,7,

%T 8,15,13,8,6,13,14,15,1,20,15,13,20,0,1,8,6,1,20,6,7,8,15,13,8,6,13,

%U 14,15,1,20,15,13,20,0,1,8,6,1,20,6,7,8,15,13,8,6,13,14,15,1,20,15,13,20

%N a(n) = n^3 mod 21.

%H G. C. Greubel, <a href="/A070483/b070483.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_21">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, 1).

%F From _G. C. Greubel_, Mar 28 2016: (Start)

%F a(n) = a(n-21).

%F G.f.: (-x -8*x^2 -6*x^3 -x^4 -20*x^5 -6*x^6 -7*x^7 -8*x^8 -15*x^9 -13*x^10 -8*x^11 -6*x^12 -13*x^13 -14*x^14 -15*x^15 -x^16 -20*x^17 -15*x^18 -13*x^19 -20*x^20)/(-1 + x^21). (End)

%t PowerMod[Range[0, 90], 3, 21] (* _G. C. Greubel_, Mar 28 2016 *)

%o (Sage) [power_mod(n,3,21 )for n in range(0, 84)] # _Zerinvary Lajos_, Oct 29 2009

%o (Magma) [Modexp(n, 3, 21): n in [0..100]]; // _Vincenzo Librandi_, Mar 29 2016

%o (PARI) a(n)=n^3%21 \\ _Charles R Greathouse IV_, Apr 06 2016

%K nonn,easy

%O 0,3

%A _N. J. A. Sloane_, May 12 2002

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Last modified March 29 11:14 EDT 2024. Contains 371278 sequences. (Running on oeis4.)