A057903 Positive integers that are not the sum of exactly two positive cubes.

1, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79

Offset

1,2

Comments

Includes the cubes themselves (since a^3 = b^3 + c^3 has no solution, by the exponent 3 case of Fermat's Last Theorem), so is different from A022555.

References

Elena Deza and Michel Marie Deza, Figurate numbers, World Scientific Publishing (2012), page 307.

Links

Table of n, a(n) for n=1..71.

Eric Weisstein's World of Mathematics, Cubic number.

Formula

Equals A022555 union A000578 - {0}.

Mathematica

pr[n_] := Select[ PowersRepresentations[n, 2, 3], FreeQ[#, 0]& ]; Select[ Range[80], pr[#] == {} &] (* Jean-François Alcover, Nov 08 2012 *)

Crossrefs

Cf. A022555, A000578.

Sequence in context: A183296 A138928 A116587 * A247833 A047310 A184530

Adjacent sequences: A057900 A057901 A057902 * A057904 A057905 A057906

Keyword

nonn

Author

Eric W. Weisstein

Extensions

Edited by N. J. A. Sloane, Sep 28 2007

Status

approved