G.f.: Sum_{k>=0} x^(k^2) * Product_{j=1..k} 1/(1 - x^j)^4.

Terms

a(0) =1a(1) =1a(2) =4a(3) =10a(4) =21a(5) =39a(6) =70a(7) =120a(8) =205a(9) =342a(10) =568a(11) =924a(12) =1490a(13) =2356a(14) =3684a(15) =5666a(16) =8619a(17) =12935a(18) =19230a(19) =28280a(20) =41260a(21) =59680a(22) =85740a(23) =122306a(24) =173447a(25) =244472a(26) =342774a(27) =478014a(28) =663391a(29) =916149