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

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, 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, 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

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

Formula

From G. C. Greubel, Mar 28 2016: (Start)

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

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)

Mathematica

PowerMod[Range[0, 90], 3, 21] (* G. C. Greubel, Mar 28 2016 *)

Prog

(Sage) [power_mod(n, 3, 21 )for n in range(0, 84)] # Zerinvary Lajos, Oct 29 2009
(Magma) [Modexp(n, 3, 21): n in [0..100]]; // Vincenzo Librandi, Mar 29 2016
(PARI) a(n)=n^3%21 \\ Charles R Greathouse IV, Apr 06 2016

Crossrefs

Sequence in context: A153493 A113212 A275008 * A124605 A272430 A021120

Adjacent sequences: A070480 A070481 A070482 * A070484 A070485 A070486

Keyword

nonn,easy

Author

N. J. A. Sloane, May 12 2002

Status

approved