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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =21a(6) =50a(7) =122a(8) =303a(9) =763a(10) =1943a(11) =4996a(12) =12953a(13) =33824a(14) =88877a(15) =234824a(16) =623474a(17) =1662618a(18) =4451171a(19) =11959159a(20) =32235236a(21) =87145035a(22) =236226761a(23) =641942519a(24) =1748479813a(25) =4772529625a(26) =13052515077a(27) =35763350619a(28) =98158386548a(29) =269844628977