OFFSET
1,2
COMMENTS
The conjecture in A266003 implies that a(n) > 0 for all n > 0.
It seems that a(n) <= n^2 for any n > 0.
LINKS
Zhi-Wei Sun, Table of n, a(n) for n = 1..10000
EXAMPLE
a(50) = 1011 since -50 = 78^4 - 1011^3 + 31565^2.
MATHEMATICA
SQ[n_]:=SQ[n]=IntegerQ[Sqrt[n]]
Do[y=Ceiling[n^(1/3)]; Label[bb]; Do[If[SQ[y^3-n-x^4], Goto[aa]], {x, 0, (n+y^3)^(1/4)}]; y=y+1; Goto[bb]; Label[aa]; Print[n, " ", y]; Continue, {n, 1, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Zhi-Wei Sun, Dec 19 2015
STATUS
approved