OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,0,2).
FORMULA
From Colin Barker, Jul 19 2013: (Start)
a(n) = 2*a(n-3) for n>5.
G.f.: -(x^5+2*x^4+2*x^3+3*x^2+2*x+1) / (2*x^3-1). (End)
Sum_{n>=0} 1/a(n) = 62/21. - Amiram Eldar, Jan 17 2022
MATHEMATICA
CoefficientList[Series[-(x^5 + 2 x^4 + 2 x^3 + 3 x^2 + 2 x + 1)/(2 x^3 - 1), {x, 0, 50}], x] (* Vincenzo Librandi, Oct 18 2013 *)
Sort[Flatten[#{1, 3, 7}&/@(2^Range[0, 20])]] (* Harvey P. Dale, Jan 30 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Jul 19 2013
STATUS
approved