OFFSET
0,1
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,5,-5).
FORMULA
G.f.: (3+4*x-5*x^2) / ((1-x)*(1-5*x^2)). - Ralf Stephan, Apr 30 2004
From Colin Barker, Nov 25 2016: (Start)
a(n) = (7*5^(n/2) - 1)/2 for n even.
a(n) = (6*5^((n+1)/2) - 2)/4 for n odd.
a(n) = a(n-1) + 5*a(n-2) - 5*a(n-3) for n>2. (End)
a(n) = (3-(-1)^n-(13+(-1)^n)*5^((1-(-1)^n+2*n)/4))/(2*(-1)^n-6). - Wesley Ivan Hurt, Oct 02 2021
MATHEMATICA
LinearRecurrence[{1, 5, -5}, {3, 7, 17}, 50] (* Paolo Xausa, Sep 16 2024 *)
PROG
(PARI) Vec((-5*x^2 + 4*x + 3)/(5*x^3 - 5*x^2 - x + 1) + O(x^40)) \\ Colin Barker, Nov 25 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved