The On-Line Encyclopedia of Integer Sequences (OEIS)

A270005 revision #6

A270005

Integers n such that 1^2 + 3^2 + 5^2 + ... + (2*n-1)^2 = x^3 + y^3 has solution for positive integers x and y.

3, 48, 813, 4697, 5694, 6752, 13773, 25477, 34989

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OFFSET

1,1

COMMENTS

Integers n such that n*(4*n^2 - 1)/3 is the sum of 2 positive cubes.

LINKS

EXAMPLE

3 is a term because 1^2 + 3^2 + 5^2 = 2^3 + 3^3.

48 is a term because 1^2 + 3^2 + 5^2 + ... + 95^2 = 31^3 + 49^3.

PROG

(PARI) isA003325(n) = for(k=1, sqrtnint(n\2, 3), ispower(n-k^3, 3) && return(1));

a000447(n) = n*(4*n^2 - 1)/3;

for(n=1, 1e5, if(isA003325(a000447(n)), print1(n, ", ")));

CROSSREFS

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Mar 08 2016

STATUS

editing