OFFSET
0,2
FORMULA
(n+2)[7+3(-1)^n]/4 * 5^[(n-1)/2].
Conjecture: a(n) = 10*a(n-2)-25*a(n-4). G.f.: -(5*x^3-3*x-1)/(5*x^2-1)^2. [Colin Barker, Oct 13 2012]
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved