Can $x^3 + 7$ ever be a square integer, for integer $x$ ? If not, how can this be proved ?
I have tested with a quick Python script and have reached $x = $ approx. 14 billion, with no squares yet found.
import gmpy2
x = 1
output_gap = 10**7
while True :
if x % output_gap == 0 :
print('x = %s' % f"{x:,}")
y = x**3 + 7
if (gmpy2.is_square(y)) :
print('Square detected at x = %s' % f"{x:,}")
x += 1