wu :: forums « wu :: forums - sum of distinct cubes » Welcome, Guest. Please Login or Register. Nov 28th, 2023, 5:06pm RIDDLES SITE WRITE MATH! Home Help Search Members Login Register wu :: forums  riddles  medium (Moderators: towr, SMQ, Icarus, william wu, Grimbal, ThudnBlunder, Eigenray)  sum of distinct cubes « Previous topic | Next topic » Author Topic: sum of distinct cubes  (Read 763 times)
Christine
Full Member    Posts: 159 sum of distinct cubes   « on: Aug 14th, 2014, 9:42am » Quote Modify

Cubes with a representation as a sum of distinct cubes :

Some end with a 1^3  : 9^3 = 8^3 + 6^3 + 1^3

others don't : 6^3 = 5^3 + 4^3 + 3^3

Is the set of those that don't finite or infinite?

How to prove it? IP Logged
towr
wu::riddles Moderator
Uberpuzzler      Some people are average, some are just mean.

Gender: Posts: 13730 Re: sum of distinct cubes   « Reply #1 on: Aug 14th, 2014, 10:08am » Quote Modify

multiply by n^3
if a^3 = b^3 + c^3 + d^3 then (an)^3 = (bn)^3 + (cn)^3 + (dn)^3 IP Logged

Wikipedia, Google, Mathworld, Integer sequence DB

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