A022556 - OEIS

%I #15 Feb 17 2023 09:27:50

%S 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,

%T 34,35,36,37,38,39,41,43,44,45,49,50,51,52,53,54,55,57,58,60,63,64,65,

%U 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

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

%H Jean-François Alcover, <a href="/A022556/b022556.txt">Table of n, a(n) for n = 1..39986</a>

%p isA022556 := proc(n)

%p     local a2,b,c ;

%p     for b from 0 do

%p         if b^3 > n then

%p             return false;

%p         end if;

%p         for c from b do

%p             a2 := n-b^3-c^3 ;

%p             if a2 < 0 then

%p                 break;

%p             end if;

%p             if issqr(a2) then

%p                 return true;

%p             end if;

%p         end do:

%p     end do:

%p end proc: # _R. J. Mathar_, Sep 02 2016

%t smax = 50000;

%t 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 *)

%Y Cf. A022557 (complement).

%K nonn

%O 1,3

%A _N. J. A. Sloane_.

%E More terms from _Jean-François Alcover_, Apr 07 2020