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

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =6a(7) =8a(8) =11a(9) =16a(10) =21a(11) =27a(12) =38a(13) =49a(14) =63a(15) =84a(16) =108a(17) =137a(18) =179a(19) =226a(20) =286a(21) =365a(22) =457a(23) =570a(24) =720a(25) =894a(26) =1106a(27) =1378a(28) =1700a(29) =2087