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A266973 a(n) = 4^n mod 17. 1
1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16, 13, 1, 4, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Period 4: repeat [1, 4, 16, 13].

LINKS

Table of n, a(n) for n=0..74.

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

FORMULA

G.f.: (1+4*x+16*x^2+13*x^3)/(1-x^4).

a(n) = a(n-4) for n>3.

From Wesley Ivan Hurt, Jun 29 2016: (Start)

a(n) = (34 - 3*(5 + 3*I)*I^(-n) - 3*(5 - 3*I)*I^n)/4 where I=sqrt(-1).

a(n) = (17 - 15*cos(n*Pi/2) - 9*sin(n*Pi/2))/2. (End)

MAPLE

A266973:=n->power(4, n) mod 17: seq(A266973(n), n=0..100); # Wesley Ivan Hurt, Jun 29 2016

MATHEMATICA

PowerMod[4, Range[0, 100], 17]

PROG

(MAGMA) [Modexp(4, n, 17): n in [0..100]];

CROSSREFS

Cf. similar sequences of the type 4^n mod p, where p is a prime: A010685 (5), A153727 (7), A168429 (11), A168430 (13), this sequence (17), A187532 (19).

Sequence in context: A224123 A273579 A147560 * A029659 A265218 A331055

Adjacent sequences:  A266970 A266971 A266972 * A266974 A266975 A266976

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Apr 06 2016

STATUS

approved

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Last modified July 8 00:40 EDT 2020. Contains 335502 sequences. (Running on oeis4.)