A001218 a(n) = 3^n mod 100.

1, 3, 9, 27, 81, 43, 29, 87, 61, 83, 49, 47, 41, 23, 69, 7, 21, 63, 89, 67, 1, 3, 9, 27, 81, 43, 29, 87, 61, 83, 49, 47, 41, 23, 69, 7, 21, 63, 89, 67, 1, 3, 9, 27, 81, 43, 29, 87, 61, 83, 49, 47, 41, 23, 69, 7, 21, 63, 89, 67

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

Period is 20.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for sequences related to final digits of numbers
• Index entries for linear recurrences with constant coefficients, signature (1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1).

Crossrefs

Cf. A001148, A216096, A216097. - Zak Seidov, Jul 27 2014

Programs

Magma

[Modexp(3, n, 100): n in [0..100]]; // Vincenzo Librandi, Aug 15 2016

Mathematica

PowerMod[3, Range[0, 60], 100] (* Vincenzo Librandi, Aug 15 2016 *)

PARI

a(n)=lift(Mod(3,100)^n) \\ Charles R Greathouse IV, Dec 27 2012

Extensions

Definition corrected by Zak Seidov, Jul 27 2014