Solution of Ljunggren Equation/Mistake

Source Work

 * The Dictionary
 * $220$
 * $220$

Mistake

 * The only solution of the equation $x^2 + 1 = 2 y^2$ is $x = 239, y = 13$.

There also exists the solution $x = 1, y = 1$.

It perhaps also needs to be pointed out that the equation is Diophantine.