A070540 a(n) = n^4 mod 21.

0, 1, 16, 18, 4, 16, 15, 7, 1, 9, 4, 4, 9, 1, 7, 15, 16, 4, 18, 16, 1, 0, 1, 16, 18, 4, 16, 15, 7, 1, 9, 4, 4, 9, 1, 7, 15, 16, 4, 18, 16, 1, 0, 1, 16, 18, 4, 16, 15, 7, 1, 9, 4, 4, 9, 1, 7, 15, 16, 4, 18, 16, 1, 0, 1, 16, 18, 4, 16, 15, 7, 1, 9, 4, 4, 9, 1, 7, 15, 16, 4, 18, 16, 1, 0, 1, 16, 18

Offset

0,3

Comments

Equivalently: n^(6*m + 4) mod 21. - G. C. Greubel, Apr 05 2016

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, Apr 05 2016: (Start)

a(21*n) = 0.

a(n+21) = a(n). (End)

Mathematica

PowerMod[Range[0, 100], 4, 21] (* G. C. Greubel, Apr 05 2016 *)

Prog

(Sage) [power_mod(n, 4, 21)for n in range(0, 88)] # Zerinvary Lajos, Oct 31 2009
(PARI) a(n)=n^4%21 \\ Charles R Greathouse IV, Apr 06 2016

Crossrefs

Sequence in context: A041542 A030046 A002925 * A341271 A374594 A358677

Adjacent sequences: A070537 A070538 A070539 * A070541 A070542 A070543

Keyword

nonn,easy

Author

N. J. A. Sloane, May 13 2002

Status

approved