A271379 a(n) = 5^n mod 101.

1, 5, 25, 24, 19, 95, 71, 52, 58, 88, 36, 79, 92, 56, 78, 87, 31, 54, 68, 37, 84, 16, 80, 97, 81, 1, 5, 25, 24, 19, 95, 71, 52, 58, 88, 36, 79, 92, 56, 78, 87, 31, 54, 68, 37, 84, 16, 80, 97, 81, 1, 5, 25, 24, 19, 95, 71, 52, 58, 88, 36, 79, 92, 56, 78

Offset: 0

Author

Vincenzo Librandi, Apr 07 2016

Keywords

• nonn
• easy

Comments

Period 25: repeat [1, 5, 25, 24, 19, 95, 71, 52, 58, 88, 36, 79, 92, 56, 78, 87, 31, 54, 68, 37, 84, 16, 80, 97, 81].

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).

Crossrefs

Cf. similar sequences listed in A271378.

Programs

Magma

[Modexp(5, n, 101): n in [0..100]];

Mathematica

PowerMod[5, Range[0, 100], 101]

PARI

a(n) = lift(Mod(5, 101)^n); \\ Altug Alkan, Apr 07 2016

Formula

G.f.: (1 +5*x +25*x^2 +24*x^3 +19*x^4 +95*x^5 +71*x^6 +52*x^7 +58*x^8 +88*x^9 +36*x^10 +79*x^11 +92*x^12 +56*x^13 +78*x^14 +87*x^15 +31*x^16 +54*x^17 +68*x^18 +37*x^19 +84*x^20 +16*x^21 +80*x^22 +97*x^23 +81*x^24)/(1-x^25).

a(n) = a(n-25).