Expansion of (1-x)/(1-4*x-6*x^2).

Terms

a(0) =1a(1) =3a(2) =18a(3) =90a(4) =468a(5) =2412a(6) =12456a(7) =64296a(8) =331920a(9) =1713456a(10) =8845344a(11) =45662112a(12) =235720512a(13) =1216854720a(14) =6281741952a(15) =32428096128a(16) =167402836224a(17) =864179921664