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

Terms

a(0) =1a(1) =6a(2) =20a(3) =56a(4) =144a(5) =352a(6) =832a(7) =1920a(8) =4352a(9) =9728a(10) =21504a(11) =47104a(12) =102400a(13) =221184a(14) =475136a(15) =1015808a(16) =2162688a(17) =4587520a(18) =9699328a(19) =20447232a(20) =42991616a(21) =90177536a(22) =188743680a(23) =394264576a(24) =822083584a(25) =1711276032a(26) =3556769792a(27) =7381975040a(28) =15300820992a(29) =31675383808