A025469 Number of partitions of n into 3 distinct positive cubes.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0

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

Antti Karttunen, Table of n, a(n) for n = 0..17073

Index entries for sequences related to sums of cubes

Formula

a(n) = A025465(n) - A025468(n). - Antti Karttunen, Aug 29 2017

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

Cf. A025465 (not necessarily distinct), A025468, A025419 (greedy inverse).

Cf. A024975 (positions of nonzero terms), A024974 (positions of terms > 1), A025399-A025402.

Sequence in context: A248805 A307721 A023976 * A025466 A072769 A353625

Adjacent sequences: A025466 A025467 A025468 * A025470 A025471 A025472

Keyword

nonn

Author

David W. Wilson

Status

approved