OFFSET
0,4
COMMENTS
Limiting ration at n=30: 3.367159464464469.
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,7,6,-8,-6,7,-1,-1).
FORMULA
G.f.: (x^4 -2*x^3 +x^2 +2*x +1) * (x^4 +2*x^3 -4*x^2 -2*x +1) / (x^8 +x^7 -7*x^6 +6*x^5 +8*x^4 -6*x^3 -7*x^2 -x +1). - Colin Barker, Oct 23 2013
MATHEMATICA
a = Table[Product[1 + 4*Cos[k*Pi/n]^2 + 16*Cos[k*Pi/n]^4 + 64*Cos[k*Pi/n]^6, {k, 1, (n - 1)/2}], {n, 0, 30}]; Round[%] FullSimplify[ExpandAll[a]]
PROG
(PARI) a(n) = round(prod(k=1, (n-1)/2, 1+4*cos(k*Pi/n)^2+16*cos(k*Pi/n)^4+64*cos(k*Pi/n)^6)) \\ Colin Barker, Oct 23 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Roger L. Bagula and Gary W. Adamson, Nov 24 2008
STATUS
approved