OFFSET
0,2
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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 1).
FORMULA
From R. J. Mathar, Apr 20 2010: (Start)
a(n) = a(n-1) - a(n-21) + a(n-22).
G.f.: ( -1-4*x -20*x^2 -14*x^3 +16*x^4 -6*x^5 +13*x^6-21*x^7 +24*x^8 -9*x^9 -2*x^10 -10*x^11 -7*x^12 +8*x^13 -3*x^14 +28*x^15 -32*x^16 +12*x^17 +17*x^18 -x^19 -5*x^20 -26*x^21 ) / ( (x-1)*(1+x)*(x^2-x+1)*(x^6-x^5+x^4-x^3+x^2-x+1)*(x^12+x^11-x^9-x^8+x^6-x^4-x^3+x+1) ). (End)
a(n) = a(n-42). - G. C. Greubel, Mar 16 2016
MATHEMATICA
PowerMod[5, Range[0, 50], 43] (* G. C. Greubel, Mar 16 2016 *)
PROG
(Sage) [power_mod(5, n, 43) for n in range(0, 74)] # Zerinvary Lajos, Nov 26 2009
(PARI) a(n)=lift(Mod(5, 43)^n) \\ Charles R Greathouse IV, Mar 22 2016
(Magma) [Modexp(5, n, 43): n in [0..80]]; // Bruno Berselli, Mar 22 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 12 2002
STATUS
approved