a(n) = [x^n] (x^5 + 5*x^4 + 4*x^3 - 3*x + 1)/((1 - x)*(x^2 + 2*x - 1)^2).

Terms

a(0) =1a(1) =2a(2) =4a(3) =10a(4) =30a(5) =90a(6) =264a(7) =754a(8) =2106a(9) =5778a(10) =15628a(11) =41786a(12) =110678a(13) =290858a(14) =759312a(15) =1971042a(16) =5091442a(17) =13095586a(18) =33555988a(19) =85695978a(20) =218198158a(21) =554081146a(22) =1403588376a(23) =3547702610a(24) =8949110954a(25) =22532603954a(26) =56637795100a(27) =142141826074a(28) =356212187334a(29) =891481312842