A070336 a(n) = 2^n mod 25.

1, 2, 4, 8, 16, 7, 14, 3, 6, 12, 24, 23, 21, 17, 9, 18, 11, 22, 19, 13, 1, 2, 4, 8, 16, 7, 14, 3, 6, 12, 24, 23, 21, 17, 9, 18, 11, 22, 19, 13, 1, 2, 4, 8, 16, 7, 14, 3, 6, 12, 24, 23, 21, 17, 9, 18, 11, 22, 19, 13, 1, 2, 4, 8, 16, 7, 14, 3, 6, 12, 24, 23, 21, 17

Offset: 0

Author

N. J. A. Sloane, May 12 2002

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1).

Programs

GAP

a:=List([0..70],n->PowerMod(2,n,25));; Print(a); # Muniru A Asiru, Jan 28 2019

Mathematica

PowerMod[2,Range[0,75],25] (* or *) LinearRecurrence[ {1,0,0,0,0,0,0,0,0,-1,1},{1,2,4,8,16,7,14,3,6,12,24}, 75] (* Harvey P. Dale, Jun 20 2011 *)

PARI

a(n)=lift(Mod(2,25)^n) \\ Charles R Greathouse IV, Mar 22 2016

Sage

[power_mod(2,n,25)for n in range(0,74)] # Zerinvary Lajos, Nov 03 2009

Formula

From R. J. Mathar, Apr 13 2010: (Start)

a(n) = a(n-1) - a(n-10) + a(n-11).

G.f.: (1+x+2*x^2+4*x^3+8*x^4-9*x^5+7*x^6 -11*x^7+3*x^8+6*x^9+13*x^10)/ ((1-x) * (x^ 2+1) * (x^8-x^6+x^4-x^2+1)). (End)

a(n) = a(n-20). - Franz Vrabec, Dec 06 2011