Earliest sequence such that xy | a(x+y) and (x+y) | a(xy) for all x >= 1, y >= 1.

Terms

a(0) =2a(1) =3a(2) =4a(3) =60a(4) =12a(5) =2520a(6) =120a(7) =5040a(8) =2520a(9) =277200a(10) =2520a(11) =4324320a(12) =27720a(13) =5045040a(14) =10810800a(15) =49008960a(16) =720720a(17) =4190266080a(18) =12252240a(19) =4655851200a(20) =4888643760a(21) =117793035360a(22) =232792560a(23) =642507465600a(24) =26771144400