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A274578 Nonsquare n such that n^3 - 1 is the average of two positive cubes. 0
2305, 2629, 4117, 7060, 37444, 46081, 113320, 208545 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The equation x^3 + y^3 = 2*z^3 has no integer solution triple (x, y, z) for x > y and z is nonzero. So this sequence focuses on the equation x^3 + y^3 = 2*(z^3 - 1) where x, y > 0.

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

2305 is a term because it is not a square and 2305^3 - 1 = (144^3 + 2904^3) / 2.

PROG

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

lista(nn) = for(n=1, nn, if(isA003325(2*(n^3-1)) && !issquare(n), print1(n, ", ")));

CROSSREFS

Cf. A000037, A003325, A068601, A273822.

Sequence in context: A259321 A223302 A174558 * A031774 A031546 A250874

Adjacent sequences:  A274575 A274576 A274577 * A274579 A274580 A274581

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Jun 29 2016

STATUS

approved

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Last modified January 18 05:09 EST 2020. Contains 330995 sequences. (Running on oeis4.)