Respuesta :

124 easy! :) (need 20 characters lol)
ur pattern is : a(n) = n^3 - 1
1^3 - 1 = 0
2^3 - 1 = 7
3^3 - 1 = 26
4^3 - 1 = 63
5^3 - 1 = 124 <== ur missing number
6^3 - 1 = 215