OFFSET
0,2
FORMULA
From Colin Barker, Jan 05 2014: (Start)
Conjecture: a(n) = 14*a(n-2) - 9*a(n-4) for n > 4.
G.f.: (9*x^4-6*x^3-10*x^2+2*x+1) / (9*x^4-14*x^2+1). (End)
MATHEMATICA
a = Table[2^n*Product[2 + 3*Cos[k*Pi/n]^2, {k, 1, (n - 1)/2}], {n, 0, 30}]; Round[%] FullSimplify[ExpandAll[a]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula and Gary W. Adamson, Nov 24 2008
STATUS
approved