OFFSET
0,1010
COMMENTS
In other words, number of solutions to the equation n = x^3 + y^3 + z^3 with x > y > z > 0. - Antti Karttunen, Aug 29 2017
LINKS
FORMULA
EXAMPLE
From Antti Karttunen, Aug 29 2017: (Start)
For n = 36 there is one solution: 36 = 27 + 8 + 1, thus a(36) = 1.
For n = 1009 there are two solutions: 1009 = 10^3 + 2^3 + 1^3 = 9^3 + 6^3 + 4^3, thus a(1009) = 2. This is also the first point where sequence attains value greater than one.
(End)
MAPLE
A025469 := proc(n)
local a, x, y, zcu ;
a := 0 ;
for x from 1 do
if 3*x^3 > n then
return a;
end if;
for y from x+1 do
if x^3+2*y^3 > n then
break;
end if;
zcu := n-x^3-y^3 ;
if zcu > y^3 and isA000578(zcu) then
a := a+1 ;
end if;
end do:
end do:
end proc:
seq(A025469(n), n=1..80) ; # R. J. Mathar, Jun 15 2018
MATHEMATICA
Table[Count[IntegerPartitions[n, {3}], _?(And[UnsameQ @@ #, AllTrue[#, IntegerQ[#^(1/3)] &]] &)], {n, 105}] (* Michael De Vlieger, Aug 29 2017 *)
PROG
(PARI) A025469(n) = { my(s=0); for(x=1, n, if(ispower(x, 3), for(y=x+1, n-x, if(ispower(y, 3), for(z=y+1, n-(x+y), if((ispower(z, 3)&&(x+y+z)==n), s++)))))); (s); }; \\ Antti Karttunen, Aug 29 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved