G.f. 1 / Product_{n>=1} (1 - x^n)^3 * (1 - x^(2*n-1))^2.

Terms

a(0) =1a(1) =5a(2) =18a(3) =55a(4) =149a(5) =371a(6) =867a(7) =1923a(8) =4086a(9) =8374a(10) =16634a(11) =32152a(12) =60669a(13) =112041a(14) =202943a(15) =361200a(16) =632647a(17) =1091917a(18) =1859225a(19) =3126242a(20) =5195715a(21) =8541624a(22) =13899866a(23) =22404091a(24) =35787815a(25) =56683294a(26) =89061028a(27) =138872410a(28) =214984454a(29) =330532633