A167426 a(n) = 2^n mod 28.

1, 2, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4, 8, 16, 4

Offset

0,2

Links

Table of n, a(n) for n=0..83.

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

Formula

a(n) = a(n-3), n>=5. - G. C. Greubel, Jun 13 2016

G.f. 1+2*x -4*x^2*(1+2*x+4*x^2) / ( (x-1)*(1+x+x^2) ). - R. J. Mathar, Jun 18 2019

Mathematica

Table[Mod[2^n, 28], {n, 0, 50}] (* G. C. Greubel, Jun 13 2016 *)
PowerMod[2, Range[0, 90], 28] (* or  *) PadRight[{1, 2}, 90, {8, 16, 4}] (* Harvey P. Dale, Mar 09 2023 *)

Prog

(Sage) [power_mod(2, n, 28)for n in range(0, 84)] #
(PARI) a(n)=lift(Mod(2, 28)^n) \\ Charles R Greathouse IV, Mar 22 2016

Crossrefs

Sequence in context: A352387 A110001 A302030 * A261702 A033491 A050076

Adjacent sequences: A167423 A167424 A167425 * A167427 A167428 A167429

Keyword

nonn,easy

Author

Zerinvary Lajos, Nov 03 2009

Status

approved