OFFSET
0,2
COMMENTS
Hankel transform is period 12, repeat (1, 0, -1, -2, -1, 0, 1, 1, 0, 0, 0, 1).
FORMULA
a(n)=sum{k=0..floor(n/2), sum{j=0..n-k, C(n-k,j)*if(k<=j, C(j+1,2*(j-k))*A000108(j-k),0)}}.
G.f.: (1-2*x-x^3-(1-x)*sqrt((x^2-3*x+1)*(x^2+x+1)))/(2*x^5). - Mark van Hoeij, May 10 2013
Conjecture: (n+5)*(n+1)*a(n) -(2*n+5)*(n+2)*a(n-1) -(n+2)*(n+1)*a(n-2) -(n+1)*(2*n+1)*a(n-3) +(n-2)*(n+2)*a(n-4)=0. - R. J. Mathar, Feb 13 2015
PROG
(PARI) x='x+O('x^66); Vec((1-2*x-x^3-(1-x)*sqrt((x^2-3*x+1)*(x^2+x+1)))/(2*x^5)) \\ Joerg Arndt, May 11 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Barry, Apr 01 2011
STATUS
approved