# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a018890 Showing 1-1 of 1 %I A018890 #35 Aug 10 2022 09:50:37 %S A018890 7,14,21,42,47,49,61,77,85,87,103,106,111,112,113,122,140,148,159,166, %T A018890 174,178,185,204,211,223,229,230,237,276,292,295,300,302,311,327,329, %U A018890 337,340,356,363,390,393,401,412,419,427,438,446,453,465,491,510,518,553,616 %N A018890 Numbers whose smallest expression as a sum of positive cubes requires exactly 7 cubes. %C A018890 It is conjectured that a(121)=8042 is the last term - _Jud McCranie_ %C A018890 An unpublished result of Deshouillers-Hennecart-Landreau, combined with Lemma 3 from Bertault, Ramaré, & Zimmermann implies that if there are any terms beyond a(121) = 8042,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 %D A018890 J. Roberts, Lure of the Integers, entry 239. %H A018890 T. D. Noe, Table of n, a(n) for n = 1..121 %H A018890 F. Bertault, O. Ramaré, and P. Zimmermann, On sums of seven cubes, Math. Comp. 68 (1999), pp. 1303-1310. %H A018890 Jan Bohman and Carl-Erik Froberg, Numerical investigation of Waring's problem for cubes, Nordisk Tidskr. Informationsbehandling (BIT) 21 (1981), 118-122. %H A018890 K. S. McCurley, An effective seven-cube theorem, J. Number Theory, 19 (1984), 176-183. %H A018890 Eric Weisstein's World of Mathematics, Cubic Number %H A018890 Eric Weisstein's World of Mathematics, Waring's Problem %H A018890 Index entries for sequences related to sums of cubes %t A018890 Select[Range[700], (pr = PowersRepresentations[#, 7, 3]; pr != {} && Count[pr, r_/; (Times @@ r) == 0] == 0)&] (* _Jean-François Alcover_, Jul 26 2011 *) %Y A018890 Cf. A004829, A018888, A018889. %K A018890 nonn,fini %O A018890 1,1 %A A018890 Anonymous # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE