%I #15 Feb 02 2019 14:14:10
%S 1,1,3,3,15,45,315,315,2835,14175,155925,467775,6081075,3869775,
%T 638512875,638512875,10854718875,8881133625,1856156927625,
%U 9280784638125,194896477400625,2143861251406875,2595200462229375
%N Denominators of the coefficients in exp(2x/(1-x)) power series.
%C Differs from A049606 at positions enumerated by A097324.
%D K. Knopp, Theory and application of infinite series, Dover, p. 547.
%D O. Perron, Über das infinitäre Verhalten der Koeffizienten einer gewissen Potenzreihe, Archiv d. Math. u. Phys. (3), Vol. 22, pp. 329-340, 1914.
%F a(n) is the denominator in Sum_{i=1..n} binomial(n-1, i-1)*2^i/i!.
%Y Cf. A067654.
%K nonn,frac
%O 1,3
%A _Benoit Cloitre_, Feb 03 2002