OFFSET
1,1
LINKS
FORMULA
From R. J. Mathar, Apr 22 2009: (Start)
a(n) = 2*a(n-2) = 5*A135530(n-1).
G.f.: 5*x*(2+x)/(1-2*x^2). (End)
From Amiram Eldar, Feb 02 2024: (Start)
Sum_{n>=1} 1/a(n) = 3/5.
Sum_{n>=1} (-1)^n/a(n) = 1/5. (End)
MATHEMATICA
LinearRecurrence[{0, 2}, {10, 5}, 50] (* Paolo Xausa, Jan 30 2024 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 21 2009
EXTENSIONS
More terms from R. J. Mathar, Apr 22 2009
STATUS
approved