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

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =4a(6) =5a(7) =9a(8) =11a(9) =22a(10) =27a(11) =49a(12) =68a(13) =115a(14) =157a(15) =279a(16) =372a(17) =628a(18) =914a(19) =1457a(20) =2070a(21) =3457a(22) =4840a(23) =7753a(24) =11442a(25) =17768a(26) =25824a(27) =41315a(28) =59008a(29) =92140