A076749 Least number which is the sum of four nonnegative cubes (not necessarily distinct and including zero) in n ways.

0, 81, 856, 1584, 4949, 5859, 13104, 20755, 34776, 21896, 46683, 46872, 81081, 77896, 151424, 143640, 116200, 231336, 216216, 369152, 420147, 314496, 373464, 375193, 483840, 648648, 353808, 497952, 995904, 687960, 975240, 1199016, 1120392, 1081080, 1434888

Offset

1,2

Links

Donovan Johnson, Table of n, a(n) for n = 1..250

G. Villemin's Almanach of Numbers, Sum of Four cubes:Multiple Representations

Example

a(3) = 856 because the latter is the smallest number expressible as the sum of four cubes in 3 distinct ways, namely 856 = 0^3 + 1^3 + 7^3 + 8^3 = 1^3 + 1^3 + 5^3 + 9^3 = 4^3 + 4^3 + 6^3 + 8^3.

Prog

(PARI) mx=10^7; v=vector(mx+1); cb=vector(216); for(j=0, 215, cb[j+1]=j^3); for(j1=1, 136, for(j2=j1, 150, s2=cb[j1]+cb[j2]; for(j3=j2, 171, s3=s2+cb[j3]; if(s3+cb[j3]>mx, next(2)); for(j4=j3, 216, s4=s3+cb[j4]; if(s4>mx, next(2)); v[s4+1]++)))); for(n=1, 68, for(j=1, mx+1, if(v[j]==n, print(n " " j-1); next(2)))) /* Donovan Johnson, Apr 16 2013 */

Crossrefs

Sequence in context: A273233 A045792 A067478 * A222995 A173810 A205047

Adjacent sequences: A076746 A076747 A076748 * A076750 A076751 A076752

Keyword

nonn

Author

Lekraj Beedassy, Nov 12 2002

Extensions

More terms from Jon E. Schoenfield, Jul 23 2006

Status

approved