Expansion of e.g.f. 2*exp(x)*(1-exp(x))/(1+exp(2*x)).

Terms

a(0) =0a(1) =-1a(2) =-1a(3) =2a(4) =5a(5) =-16a(6) =-61a(7) =272a(8) =1385a(9) =-7936a(10) =-50521a(11) =353792a(12) =2702765a(13) =-22368256a(14) =-199360981a(15) =1903757312a(16) =19391512145a(17) =-209865342976