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A022552
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Numbers that are not the sum of 2 squares and a nonnegative cube.
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21
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7, 15, 22, 23, 39, 55, 70, 71, 78, 87, 94, 103, 111, 115, 119, 120, 139, 167, 211, 254, 263, 267, 279, 286, 302, 311, 312, 331, 335, 342, 391, 403, 435, 454, 455, 470, 475, 499, 518, 559, 590, 595, 598, 622, 643, 659, 691, 695, 715, 727, 771
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graph;
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listen;
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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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There are 434 terms < 6 * 10^7 of which the largest is 5042631 ~= 5 * 10^6. Is this sequence finite? - David A. Corneth, Jun 23 2018
For n = 1..434, a(n) + 2 is a term of A022551. Zhi-Wei Sun conjectures that Any n can be written as x^2 + y^2 + z^3 + 0(or 2). - XU Pingya, Jun 02 2020
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LINKS
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MAPLE
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isA022552 := proc(n)
not isA022551(n) ;
end proc:
n := 1:
for c from 0 do
if isA022552(c) then
printf("%d %d\n", n, c);
n := n+1 ;
end if;
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MATHEMATICA
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max = 10^6;
Table[x^2 + y^2 + z^3, {x, 0, Sqrt[max]}, {y, x, Sqrt[max - x^2]}, {z, 0, (max - x^2 - y^2)^(1/3)}] // Flatten // Union // Select[#, # <= max&]& // Complement[Range[max], #]& (* Jean-François Alcover, Mar 23 2020 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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