You need 4150 exp

An oak aide in a big building east of fuchsia city has exp share you need to record 50 Pokemon in your pokedex and show him that, he gives you exp share for your accomplishment.

Once you get 35 Pokemon in your PokeDex, Prof. Rowan's aid will give you the Exp. Share in Eterna City's gatehouse.

the exp share lets u get points to the Pokemon that's holding the ex.p share they get double of wat the normal Pokemon got

By using the chain rule. Since the derivative of exp(x) is exp(x), the derivative of exp(exp(exp(x))) is exp(exp(exp(x))) times the derivative of what is inside the parentheses, i.e., exp(exp(exp(x))) times derivate of exp(exp(x)). Continue using the chain rule once more, for this expression.