OFFSET
0,2
FORMULA
D-finite with recurrence: a(n+2) = 4*(2*n+3)*a(n+1) -(n+1)^2*a(n); a(0)=1, a(1)=4. - Sergei N. Gladkovskii, Sep 12 2012
a(n) ~ sqrt(2)*n^n/(sqrt(8*sqrt(15)-30)*exp(n)*(4-sqrt(15))^n). - Vaclav Kotesovec, Jun 27 2013
MAPLE
a:= n-> n! *coeff(series(1/sqrt(1-8*x+x^2), x, n+1), x, n):
seq (a(n), n=0..20); # Alois P. Heinz, Sep 12 2012
MATHEMATICA
CoefficientList[Series[1/Sqrt[1-8*x+x^2], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Jun 27 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved