Special cases : a(5k+1)=abs(A065923(3k)); a(5k+3)=abs(A065923(3k+2)) where A065923(n)=y(n, -3) where y(n, x)=sum (k=0, n, (n+k)!*(x/2)^k/((n-k)!*k!))
MATHEMATICA
Denominator[Convergents[E^(2/3), 20]] (* Harvey P. Dale, Dec 01 2013 *)
PROG
(PARI) a(n)=component(component(contfracpnqn(contfrac(exp(2/3), n)), 1), 2) \\ (Warning: this will give only a limited number of correct terms, depending on the precision used. - The Editors, Oct 13 2009. See A078976 for better code.)
