G.f.: Product_{i>=1, j>=1, k>=1} (1 + x^(i*j*k)).

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =12a(5) =21a(6) =43a(7) =70a(8) =127a(9) =215a(10) =364a(11) =591a(12) =989a(13) =1562a(14) =2515a(15) =3954a(16) =6194a(17) =9538a(18) =14754a(19) =22349a(20) =33926a(21) =50910a(22) =76102a(23) =112721a(24) =166747a(25) =244205a(26) =356984a(27) =518344a(28) =749924a(29) =1078711