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A025411 Numbers that are the sum of 4 distinct positive cubes.

%I A025411 #19 Jun 26 2023 05:32:54
%S A025411 100,161,198,217,224,252,289,308,315,350,369,376,379,406,413,416,432,
%T A025411 435,442,477,496,503,533,540,548,559,568,585,587,594,604,611,624,631,
%U A025411 646,650,665,672,685,692,702,709,711,728,737,748,756,763,765,793,800,802,819,821,828,854,861,863,864,880,882,883,889,890,917,919,920,926,927,945,946,954,973,980,981,988,1007,1010,1017,1036
%N A025411 Numbers that are the sum of 4 distinct positive cubes.
%C A025411 First differs from A025408 at a(80)=1036. - _Ray Chandler_, Feb 19 2005
%e A025411 a(80) = 1036 = 1+8+27+1000 = 27+64+216+729.
%p A025411 isA025411:= proc(n)
%p A025411     local a, x, y, z,wcu ;
%p A025411     for x from 1 do
%p A025411         if 4*x^3 > n then
%p A025411             return false;
%p A025411             end if;
%p A025411         for y from x+1 do
%p A025411             if x^3+3*y^3 > n then
%p A025411                 break;
%p A025411             end if;
%p A025411             for z from y+1 do
%p A025411                 if x^3+y^3+2*z^3 > n then
%p A025411                     break;
%p A025411                 end if;
%p A025411                 wcu := n-x^3-y^3-z^3 ;
%p A025411                 if wcu > z^3 and isA000578(wcu) then
%p A025411                     return true ;
%p A025411                 end if;
%p A025411             end do
%p A025411         end do:
%p A025411     end do:
%p A025411 end proc:
%p A025411 for n from 1 to 1100 do
%p A025411     if isA025411(n) then
%p A025411         printf("%d,",n) ;
%p A025411     end if;
%p A025411 end do: # _R. J. Mathar_, Jun 15 2018
%t A025411 smax = 1036;
%t A025411 imax = smax^(1/3) // Ceiling;
%t A025411 Table[If[Less[i, j, k, l] && (s = i^3 + j^3 + k^3 + l^3) <= smax, s, Nothing], {i, 1, imax}, {j, i+1, imax}, {k, j+1, imax}, {l, k+1, imax}] // Flatten // Union (* _Jean-François Alcover_, Jun 26 2023 *)
%Y A025411 Cf. A025408, A025409, A025410, A025412, A025413.
%K A025411 nonn
%O A025411 1,1
%A A025411 _David W. Wilson_
%E A025411 More terms from _Ray Chandler_, Feb 19 2005