

A018890


Smallest expression as sum of positive cubes requires exactly 7 cubes.


6



7, 14, 21, 42, 47, 49, 61, 77, 85, 87, 103, 106, 111, 112, 113, 122, 140, 148, 159, 166, 174, 178, 185, 204, 211, 223, 229, 230, 237, 276, 292, 295, 300, 302, 311, 327, 329, 337, 340, 356, 363, 390, 393, 401, 412, 419, 427, 438, 446, 453, 465, 491, 510, 518, 553, 616
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OFFSET

1,1


COMMENTS

An unpublished result of DeshouillersHennecartLandreau, combined with Lemma 3 from Bertault, Ramaré, & Zimmermann implies that if there are any terms beyond a(121) = 8042, they are greater than 1.62 * 10^34.  Charles R Greathouse IV, Jan 23 2014


REFERENCES

J. Bohman and C.E. Froberg, Numerical investigation of Waring's problem for cubes, Nordisk Tidskr. Informationsbehandling (BIT) 21 (1981), 118122.
J. Roberts, Lure of the Integers, entry 239.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..121
F. Bertault, O. Ramaré, and P. Zimmermann, On sums of seven cubes, Math. Comp. 68 (1999), pp. 13031310.
K. S. McCurley, An effective sevencube theorem, J. Number Theory, 19 (1984), 176183.
Eric Weisstein's World of Mathematics, Cubic Number
Eric Weisstein's World of Mathematics, Waring's Problem
Index entries for sequences related to sums of cubes


MATHEMATICA

Select[Range[700], (pr = PowersRepresentations[#, 7, 3]; pr != {} && Count[pr, r_/; (Times @@ r) == 0] == 0)&] (* JeanFrançois Alcover, Jul 26 2011 *)


CROSSREFS

Cf. A004829, A018888, A018889.
Sequence in context: A100451 A028555 A061823 * A118502 A190367 A246172
Adjacent sequences: A018887 A018888 A018889 * A018891 A018892 A018893


KEYWORD

nonn,fini,nice


AUTHOR

Anon


EXTENSIONS

It is conjectured that a(121)=8042 is the last term  Jud McCranie


STATUS

approved



