OFFSET
1,1
COMMENTS
Values y such that x^2+y^2 = z^3 has a solution 1<=x<=y with integer x, y and z.
The positive values of A033431 are a subsequence, induced by solutions where x=y.
There are entries which have more than one representation, e.g., 10^2 + 198^2 = 34^3 and 107^2 + 198^2 = 37^3 both with y=198. 234^2 + 415^2 = 61^3 and 320^2 + 415^2 = 65^3 both with y=415.
The ordered sequence of x can apparently be constructed by retrieving the perfect squares in A106265 and printing their square roots: 1, 2, 5, 7, 8, 9, 10, 11, 16, 17, 18 , 26, 27, 30,...
EXAMPLE
2^2+2^2=2^3, so 2 is in. 5^2+10^2=5^3, so 10 is in. 2^2+11^2 = 5^3, so 11 is in. 16^2+16^2=8^3, so 16 is in.
MAPLE
isA282093 := proc(y)
local x, z3 ;
for x from 1 to y do
z3 := x^2+y^2 ;
if isA000578(z3) then
return true ;
end if;
end do:
return false ;
end proc:
for y from 1 to 800 do
if isA282093(y) then
printf("%d, \n", y) ;
end if;
end do:
MATHEMATICA
isA282093[y_] := Module[{x, z3},
For[x = 1, x <= y, x++, z3 = x^2+y^2; If[IntegerQ[z3^(1/3)], Return[True]]]; Return[False]];
Reap[For[y = 1, y <= 800, y++, If[isA282093[y], Print[y]; Sow[y]]]][[2, 1]] (* Jean-François Alcover, May 29 2023, after R. J. Mathar *)
CROSSREFS
KEYWORD
nonn
AUTHOR
R. J. Mathar, Feb 06 2017
STATUS
approved