The return of dupe hunting, pt. 1
Max Alekseyev
maxale at gmail.com
Mon Sep 24 09:22:23 CEST 2007
On 9/24/07, Andrew Plewe <aplewe at sbcglobal.net> wrote:
> I see that now looking at these two sequences, but it's not obvious to
> me from their definitions or the wording that they're supposed to be
> different. Namely, I don't get why the cubes are absent from A022555
> while they're included in A057903.
Note that a cube x^3 is "the sum of 2 nonnegative cubes" since x^3 =
x^3 + 0^3. Hence, the cubes are not in A022555.
On the other hand, a cube x^3 is not "the sum of exactly two positive
cubes" by Fermat Last Theorem (well, by the 3rd degree case of FLT).
Hence, the cubes are in A057903.
Regards,
Max
More information about the SeqFan
mailing list