Series expansion of x*(x+3)^2/(3*x+1)^2.

Terms

a(0) =0a(1) =9a(2) =-48a(3) =208a(4) =-816a(5) =3024a(6) =-10800a(7) =37584a(8) =-128304a(9) =431568a(10) =-1434672a(11) =4723920a(12) =-15431472a(13) =50073552a(14) =-161558064a(15) =518686416a(16) =-1658095920a(17) =5280397776a(18) =-16759523376a(19) =53033560272a(20) =-167365651248a(21) =526891865040