cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A001239 Numbers that are the sum of 3 nonnegative cubes in more than 1 way.

Original entry on oeis.org

216, 251, 344, 729, 855, 1009, 1072, 1366, 1457, 1459, 1520, 1674, 1728, 1729, 1730, 1737, 1756, 1763, 1793, 1854, 1945, 2008, 2072, 2241, 2414, 2456, 2458, 2729, 2736, 2752, 3060, 3391, 3402, 3457, 3500, 3592, 3599, 3655, 3744, 3745
Offset: 1

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References

  • G. H. Hardy, Ramanujan, Cambridge Univ. Press, 1940, p. 12.
  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Books, NY, 1986, p. 165.

Crossrefs

Programs

  • Mathematica
    Select[Range[4000], Length[PowersRepresentations[#, 3, 3]] > 1 &] (* Harvey P. Dale, Feb 03 2011 *)
  • PARI
    is(n)=my(t); for(a=0, sqrtnint(n, 3), my(a3=a^3, c); for(b=0, min(a, sqrtnint(n-a3, 3)), if(ispower(n-a3-b^3, 3, &c) && c <= b && t++>1, return(1)))); 0 \\ Charles R Greathouse IV, Jul 02 2017