OFFSET
0,1
LINKS
FORMULA
G.f.: (4+9x)/((1-x)*(1+x)). - R. J. Mathar, Nov 21 2011
From Wesley Ivan Hurt, Dec 31 2023: (Start)
a(n) = a(n-2) for n>1 with a(0)=4, a(1)=9.
a(n) = (13-5*(-1)^n)/2. (End)
MATHEMATICA
Table[4 + 5 Mod[n, 2], {n, 0, 50}] (* Jinyuan Wang, Feb 26 2020 *)
PROG
(PARI) a(n)=4+n%2*5 \\ Charles R Greathouse IV, Dec 21 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved