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A070483 a(n) = n^3 mod 21. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

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 xrange(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

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Last modified July 21 22:00 EDT 2019. Contains 325200 sequences. (Running on oeis4.)