Revert transform of 2*x*(1 - x - x^3)-x/(1+x).

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =45a(5) =195a(6) =887a(7) =4169a(8) =20093a(9) =98757a(10) =493123a(11) =2494491a(12) =12756393a(13) =65838591a(14) =342513423a(15) =1794185745a(16) =9455438585a(17) =50097517625a(18) =266696171475