G.f.: Sum_{k>=0} x^k * Product_{j=1..5*k} (1 + x^j)/(1 - x^j).

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =15a(5) =29a(6) =53a(7) =91a(8) =151a(9) =243a(10) =381a(11) =585a(12) =881a(13) =1305a(14) =1907a(15) =2753a(16) =3931a(17) =5559a(18) =7793a(19) =10835a(20) =14955a(21) =20501a(22) =27921a(23) =37801a(24) =50889a(25) =68139a(26) =90777a(27) =120353a(28) =158827a(29) =208683