19 Apr
2012
19 Apr
'12
3:06 p.m.
On 4/19/2012 4:54 PM, Allan Wechsler wrote:
Wait a sec, I'm being stupid. Ternary odd-digit numbers also have only 1's, so they are of the form (3^n-1)/2. If (3^n-1)/2 is a cube, then 3^n = 2m^3 + 1. OK, I'm stuck again. Fred?
Cubes are -1, 0 or 1 mod 9, so the equation has no solutions for n >= 2. -- Fred W. Helenius fredh@ix.netcom.com