OFFSET
1,1
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
EXAMPLE
91 = 3^3 + 4^3 = (-5)^3 + 6^3; 152 = 3^3 + 5^3 = (-4)^3 + 6^3; 189 = 4^3 + 5^3 = (-3)^3 + 6^3; ...
MATHEMATICA
ok[n_] := If[Length[PowersRepresentations[n, 2, 3]] >= 2, True, r = Reduce[n == x^3 + y^3, {x, y}, Integers]; If[r === False, False, Length[Union[Sort /@ ({x, y} /. {ToRules[r]})]] >= 2]]; Select[Range[13860], If[ok[#], Print[#]; True, False] &] (* Jean-François Alcover, Apr 11 2011 *)
PROG
(PARI) is(n)=#thue(thueinit(z^3+1), n)>=2 \\ Ralf Stephan, Oct 18 2013
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
EXTENSIONS
Extended by Ray Chandler, Jan 30 2009
STATUS
approved