Expansion of Product_{i>=1, j>=1} (1 + i*j*x^(i*j)).

Terms

a(0) =1a(1) =1a(2) =4a(3) =10a(4) =22a(5) =50a(6) =115a(7) =231a(8) =470a(9) =995a(10) =1912a(11) =3745a(12) =7222a(13) =13608a(14) =25345a(15) =47322a(16) =85654a(17) =155163a(18) =278867a(19) =494080a(20) =870618a(21) =1524769a(22) =2640527a(23) =4549564a(24) =7802037a(25) =13251684a(26) =22412317a(27) =37706268a(28) =63015263a(29) =104800015