OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..550
Index entries for linear recurrences with constant coefficients, signature (0,15,0,-32,0,15,0,-1).
FORMULA
G.f.: (x-1)*(1+x)*(x^4+x^3-6*x^2+x+1) / (-x^8+15*x^6-32*x^4+15*x^2-1).
MAPLE
a:= n-> (<<0|1|0|0>, <0|0|1|0>, <0|0|0|1>, <-1|15|-32|15>>^iquo(n, 2, 'r').
`if`(r=0, <<8, 1, 1, 8>>, <<1, 0, 1, 15>>))[3, 1]:
seq(a(n), n=0..30);
MATHEMATICA
a[n_] := Product[2(2+Cos[2 j Pi/(n+1)]+Cos[k Pi/3]), {k, 1, 2}, {j, 1, n/2} ] // Round;
Table[a[n], {n, 0, 24}] (* Jean-François Alcover, Aug 19 2018, after A099390 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Apr 15 2011
STATUS
approved