The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A003325

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A003325

Numbers that are the sum of 2 positive cubes.
(history; published version)

#103 by Robert Israel at Fri Sep 20 10:25:13 EDT 2024

COMMENTS

Fermat's Last Theorem is not needed for this: just note that x^3 + y^3 = (x + y) * (x^2 - x*y + y^2). - Robert Israel, Sep 19 2024

MAPLE

N:= 10^4: # to get terms <= N

sort(convert({seq(seq(x^3 + y^3, y = 1 .. floor((N-x^3)^(1/3))), x=1..floor(N^(1/3)))}, list)); # Robert Israel, Sep 19 2024

KEYWORD

nonn,easy,nice,changed

STATUS

proposed

approved

#102 by Robert Israel at Thu Sep 19 21:53:36 EDT 2024

STATUS

editing

proposed

Discussion

Thu Sep 19

23:04

Charles R Greathouse IV: Maybe it’s just late but I don’t see how that follows from the factorization.

Fri Sep 20

05:51

N. J. A. Sloane: Yes, I agree , not clear.  Maybe there was a confusion about the definition.  This definition does not say "primes"

#101 by Robert Israel at Thu Sep 19 21:53:25 EDT 2024

MAPLE

N:= 10^4: # to get terms <= N

sort(convert({seq(seq(x^3 + y^3, y = 1 .. floor((N-x^3)^(1/3))), x=1..floor(N^(1/3)))}, list)); # Robert Israel, Sep 19 2024

STATUS

proposed

editing

#100 by Robert Israel at Thu Sep 19 21:50:24 EDT 2024

STATUS

editing

proposed

#99 by Robert Israel at Thu Sep 19 21:50:16 EDT 2024

COMMENTS

Fermat's Last Theorem is not needed for this: just note that x^3 + y^3 = (x + y) * (x^2 - x*y + y^2). - Robert Israel, Sep 19 2024

STATUS

approved

editing

#98 by Jon E. Schoenfield at Sun Oct 29 00:32:06 EDT 2023

STATUS

editing

approved

#97 by Jon E. Schoenfield at Sun Oct 29 00:32:04 EDT 2023

LINKS

N. J. A. Sloane, <a href="/A003325/b003325.txt">Table of n, a(n) for n = 1..20000</a> [First (first 1000 terms from T. D. Noe])

STATUS

approved

editing

#96 by Charles R Greathouse IV at Thu Dec 01 22:11:26 EST 2022

STATUS

editing

approved

#95 by Charles R Greathouse IV at Thu Dec 01 22:11:10 EST 2022

CROSSREFS

Subsequence of A004999 and hence of A045980; supersequence of A004999 and of A202679.

#94 by Charles R Greathouse IV at Thu Dec 01 22:10:38 EST 2022

CROSSREFS

Subsequence of A045980; supersequence of A004999 and of A202679.

Cf. A024670 (2 distinct cubes), A003072, A001235, A011541, A003826, A010057, A000578, A027750, A010052, A004999, A085323 (n such that a(n+1)=a(n)+1).

STATUS

approved

editing