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 (4,0,4).
FORMULA
a(n) = Sum_{k=0..floor(n/2)} C(n-2*k, k)*4^(n-2*k).
a(n) = 4*a(n-1) + 4*a(n-3). - G. C. Greubel, Apr 29 2017
MATHEMATICA
CoefficientList[Series[1/(1 - 4*x - 4*x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[{4, 0, 4}, {1, 4, 16}, 50] (* G. C. Greubel, Apr 29 2017 *)
PROG
(PARI) x='x+O('x^50); Vec(1/(1 - 4*x - 4*x^3)) \\ G. C. Greubel, Apr 29 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Nov 18 2003
STATUS
approved