A022556 Numbers that are a sum of a square and 2 nonnegative cubes.

0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 16, 17, 18, 20, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 43, 44, 45, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 65, 66, 68, 69, 70, 71, 72, 73, 74, 76, 77, 79, 80, 81, 82, 83, 84, 88, 89, 90, 91, 92, 95, 97, 99, 100

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Jean-François Alcover, Table of n, a(n) for n = 1..39986

Crossrefs

Cf. A022557 (complement).

Programs

Maple

isA022556 := proc(n)
    local a2,b,c ;
    for b from 0 do
        if b^3 > n then
            return false;
        end if;
        for c from b do
            a2 := n-b^3-c^3 ;
            if a2 < 0 then
                break;
            end if;
            if issqr(a2) then
                return true;
            end if;
        end do:
    end do:
end proc: # R. J. Mathar, Sep 02 2016

Mathematica

smax = 50000;
Table[s = i^2 + j^3 + k^3; If[s <= smax, s, Nothing], {i, 0, Sqrt[smax] // Ceiling}, {j, 0, smax^(1/3) // Ceiling}, {k, j, smax^(1/3) // Ceiling}] // Flatten // Union (* Jean-François Alcover, Feb 17 2023 *)

Extensions

More terms from Jean-François Alcover, Apr 07 2020