A187532 a(n) = 4^n mod 19.

1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5, 1, 4, 16, 7, 9, 17, 11, 6, 5

Offset

0,2

Comments

Period 9: repeat (1,4,16,7,9,17,11,6,5).

Also continued fraction expansion of (13140908+sqrt(323139488118562))/24969762. - Bruno Berselli, Sep 09 2011

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

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

Formula

a(n+9) = a(n).

G.f.: (1 + 4*x + 16*x^2 + 7*x^3 + 9*x^4 + 17*x^5 + 11*x^6 + 6*x^7 + 5*x^8)/((1-x)*(1+x+x^2)*(1+x^3+x^6)). - Bruno Berselli, Sep 09 2011

Mathematica

PowerMod[4, Range[0, 100], 19]  (* or *)
PadRight[{}, 100, {1, 4, 16, 7, 9, 17, 11, 6, 5}] (* Paolo Xausa, Mar 17 2024 *)

Prog

(Magma) [4^n mod 19 : n in [0..80]]; // Vincenzo Librandi, Sep 09 2011
(PARI) a(n)=lift(Mod(4, 19)^n) \\ Charles R Greathouse IV, Mar 22 2016

Crossrefs

Cf. A036120, A070342, A070373, A070395, A070421.

Sequence in context: A050080 A329068 A328755 * A335353 A110651 A253890

Adjacent sequences: A187529 A187530 A187531 * A187533 A187534 A187535

Keyword

nonn,easy

Author

M. F. Hasler, Mar 10 2011

Status

approved