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

Terms

a(0) =1a(1) =3a(2) =6a(3) =9a(4) =12a(5) =15a(6) =18a(7) =21a(8) =24a(9) =27a(10) =30a(11) =33a(12) =36a(13) =39a(14) =42a(15) =45a(16) =48a(17) =51a(18) =54a(19) =57a(20) =60a(21) =63a(22) =66a(23) =69a(24) =72a(25) =75a(26) =78a(27) =81a(28) =84a(29) =87