OFFSET
0,2
COMMENTS
lim_{n -> infinity} a(n)/a(n-1) = 16.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (20, -64).
FORMULA
a(n) = (5*16^n - 4^n)/4.
G.f.: (1-x)/((1-4*x)*(1-16*x)).
E.g.f.: (1/4)*(5*exp(16*x) - exp(4*x)). - G. C. Greubel, May 29 2016
MATHEMATICA
LinearRecurrence[{20, -64}, {1, 19}, 20] (* Harvey P. Dale, Aug 24 2014 *)
PROG
(Magma) [ n le 2 select 18*n-17 else 20*Self(n-1)-64*Self(n-2): n in [1..17] ];
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Oct 25 2009
STATUS
approved