OFFSET
0,2
COMMENTS
The denominator is a parameterization of the Alexander polynomial for the knot 6_3. The g.f. is the image of the g.f. of A057083 under the Chebyshev transform A(x)->(1/(1+x^2))A(x/(1+x^2)).
LINKS
Dror Bar-Natan, The Rolfsen Knot Table
Index entries for linear recurrences with constant coefficients, signature (3,-5,3,-1).
FORMULA
G.f.: (1+x^2)/(1-3x+5x^2-3x^3+x^4); a(n)=sum{k=0..floor(n/2), C(n-k, k)(-1)^k*sum{j=0..n-2k, C(n-2k-j, j)(-3)^j*3^(n-2k-2j)}}; a(n)=sum{k=0..floor(n/2), C(n-k, k)(-1)^k*A057083(n-2k)); a(n)=sum{k=0..n, binomial((n+k)/2, k)(-1)^((n-k)/2)(1+(-1)^(n+k))A057083(k)/2}; a(n)=sum{k=0..n, A099447(n-k)*binomial(1, k/2)(1+(-1)^k)/2};
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Oct 16 2004
STATUS
approved