OFFSET
1,2
COMMENTS
For denominators see: A084057 (= product of Lucas numbers (excluding first number (2)), and powers of 2).
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (2,4).
FORMULA
From Colin Barker, Jun 20 2012: (Start)
a(n) = 2*a(n-1) + 4*a(n-2).
G.f.: 5*x^2/(1-2*x-4*x^2). (End)
a(n) = 5*A063727(n-1). - R. J. Mathar, Mar 08 2021
MATHEMATICA
LinearRecurrence[{2, 4}, {0, 5}, 30] (* Harvey P. Dale, Mar 01 2016 *)
PROG
(PARI) a(n)=5*fibonacci(n-1)*2^(n-2) \\ Franklin T. Adams-Watters, Aug 06 2009
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mark Dols, Jul 24 2009
EXTENSIONS
More terms from Franklin T. Adams-Watters, Aug 06 2009
STATUS
approved