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

Terms

a(0) =1a(1) =12a(2) =72a(3) =324a(4) =1296a(5) =4860a(6) =17496a(7) =61236a(8) =209952a(9) =708588a(10) =2361960a(11) =7794468a(12) =25509168a(13) =82904796a(14) =267846264a(15) =860934420a(16) =2754990144a(17) =8781531084a(18) =27894275208a(19) =88331871492a(20) =278942752080a(21) =878669669052