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