The conjecture made by Belgian mathematician Eugène Charles Catalan in 1844 that 8 and 9 (2^3 and 3^2) are the only consecutive powers (excluding 0 and 1). In other words,
3^2-2^3=1
(1)
is the only nontrivial solution to Catalan's Diophantine problem
x^p-y^q=+/-1.
(2)
The special case p=3 and q=2 is the n=+/-1 case of a Mordell curve.