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A070539 a(n) = n^4 mod 20. 1
0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16, 1, 16, 1, 0, 1, 16, 1, 16, 5, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Equivalently: n^(4*m + 4) mod 20. - G. C. Greubel, Apr 05 2016

LINKS

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

FORMULA

From G. C. Greubel, Apr 05 2016: (Start)

a(10*n) = 0.

a(n+10) = a(n).

G.f.: (x +16*x^2 +x^3 +16*x^4 +5*x^5 +16*x^6 +x^7 +16*x^8 +x^9)/(1 - x^10). (End)

MATHEMATICA

PowerMod[Range[0, 100], 4, 20] (* G. C. Greubel, Apr 05 2016 *)

PROG

(Sage) [power_mod(n, 4, 20)for n in range(0, 87)] # Zerinvary Lajos, Oct 31 2009

(PARI) a(n)=n^4%20 \\ Charles R Greathouse IV, Apr 05 2016

CROSSREFS

Sequence in context: A141682 A040270 A303327 * A301909 A070583 A133821

Adjacent sequences:  A070536 A070537 A070538 * A070540 A070541 A070542

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 13 2002

STATUS

approved

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Last modified August 9 17:13 EDT 2022. Contains 356026 sequences. (Running on oeis4.)