If $n\equiv 4 \pmod 9$ then $n$ cannot be written as sum of three cubes?
Solution 1:
HINT Note that $m^3 \equiv 0, \pm1 \pmod9$.
If $n\equiv 4 \pmod 9$ then $n$ cannot be written as sum of three cubes?
Solution 1:
HINT Note that $m^3 \equiv 0, \pm1 \pmod9$.