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A025411
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Numbers that are the sum of 4 distinct positive cubes.
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3
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100, 161, 198, 217, 224, 252, 289, 308, 315, 350, 369, 376, 379, 406, 413, 416, 432, 435, 442, 477, 496, 503, 533, 540, 548, 559, 568, 585, 587, 594, 604, 611, 624, 631, 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
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listen;
history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(80) = 1036 = 1+8+27+1000 = 27+64+216+729.
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MAPLE
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isA025411:= proc(n)
local a, x, y, z, wcu ;
for x from 1 do
if 4*x^3 > n then
return false;
end if;
for y from x+1 do
if x^3+3*y^3 > n then
break;
end if;
for z from y+1 do
if x^3+y^3+2*z^3 > n then
break;
end if;
wcu := n-x^3-y^3-z^3 ;
if wcu > z^3 and isA000578(wcu) then
return true ;
end if;
end do
end do:
end do:
end proc:
for n from 1 to 1100 do
if isA025411(n) then
printf("%d, ", n) ;
end if;
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MATHEMATICA
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smax = 1036;
imax = smax^(1/3) // Ceiling;
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 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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