OFFSET
0,2
FORMULA
G.f.: ( (1+x)/(1-x)/(1-6*x+x^2)*(1-x-(1-6*x+x^2)^(1/2))/2/x )^(1/2).
a(n) ~ (1 + sqrt(2))^(2*n + 3/2) / (2*sqrt(Pi*n)). - Vaclav Kotesovec, Oct 18 2020
PROG
(PARI) {a(n)=local(x=X+X*O(X^n)); polcoeff( (2*(1+x)/(1-x)/(1-6*x+x^2)/(1-x+(1-6*x+x^2)^(1/2)) )^(1/2), n, X)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 22 2005
STATUS
approved