a(n) = [x^n] Product_{k>=1} (1 + n*x^k).

Terms

a(0) =1a(1) =1a(2) =2a(3) =12a(4) =20a(5) =55a(6) =294a(7) =497a(8) =1224a(9) =2520a(10) =14410a(11) =21912a(12) =54300a(13) =104286a(14) =220710a(15) =1105215a(16) =1697552a(17) =3839382a(18) =7356762a(19) =14873580a(20) =26275620a(21) =132112596a(22) =188666126a(23) =423247104a(24) =772560600a(25) =1535398150a(26) =2632049290a(27) =4975242048a(28) =21273166572a(29) =30649985160