A083529 - OEIS

A083529

a(n) = 5^n mod 3*n.

2, 1, 8, 1, 5, 1, 5, 1, 26, 25, 5, 1, 5, 25, 35, 1, 5, 1, 5, 25, 62, 25, 5, 1, 50, 25, 80, 37, 5, 55, 5, 1, 26, 25, 80, 1, 5, 25, 8, 25, 5, 1, 5, 97, 80, 25, 5, 1, 68, 25, 125, 1, 5, 1, 155, 25, 125, 25, 5, 145, 5, 25, 188, 1, 5, 181, 5, 13, 125, 205, 5, 1, 5, 25, 125, 169, 80, 181, 5

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OFFSET

1,1

COMMENTS

From Robert Israel, Dec 25 2014: (Start)

a(n) == (-1)^n mod 3.

a(n) = 1 if and only if n is even and in A067946.

For n > 3, a(n) = 5 if and only if n is odd and in A123091. (End)

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

a(3) = 8 because 5^3 = 125 and 125 mod (3 * 3) = 8.

a(4) = 1 because 5^4 = 625 and 625 mod (3 * 4) = 1.

MAPLE

seq(5 &^n mod 3*n, n = 1 .. 1000); # Robert Israel, Dec 25 2014

MATHEMATICA

Table[Mod[5^w, 3 * w], {w, 100}]

Table[PowerMod[5, n, 3n], {n, 80}] (* Harvey P. Dale, Jul 26 2014 *)

PROG

(PARI) a(n)=lift(Mod(5, 3*n)^n) \\ Charles R Greathouse IV, Oct 03 2016

(Magma) [Modexp(5, n, 3*n): n in [1..80]]; // Vincenzo Librandi, Oct 19 2018

CROSSREFS

Cf. A000079, A000244, A000351, A000420, A082511, A083528, A083530, A067946, A123091.

Sequence in context: A254027 A284346 A318651 * A102208 A371650 A369779

Adjacent sequences: A083526 A083527 A083528 * A083530 A083531 A083532

KEYWORD

easy,nonn

AUTHOR

Labos Elemer, Apr 30 2003

STATUS

approved