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

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =10a(5) =15a(6) =24a(7) =36a(8) =52a(9) =76a(10) =109a(11) =152a(12) =211a(13) =290a(14) =393a(15) =530a(16) =709a(17) =938a(18) =1236a(19) =1618a(20) =2102a(21) =2720a(22) =3500a(23) =4477a(24) =5707a(25) =7242a(26) =9146a(27) =11511a(28) =14435a(29) =18030