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

Terms

a(0) =1a(1) =5a(2) =17a(3) =48a(4) =123a(5) =300a(6) =714a(7) =1679a(8) =3925a(9) =9149a(10) =21296a(11) =49537a(12) =115192a(13) =267824a(14) =622653a(15) =1447533a(16) =3365149a(17) =7823068a(18) =18186475a(19) =42278476a(20) =98285586a(21) =228486323a(22) =531166317a(23) =1234811937a(24) =2870589548a(25) =6673311137a(26) =15513566304a(27) =36064666240a(28) =83840177305