a,b,c,d = 正整数\(a^3 + b^3 + c^3 - d^3 = n\)。n能跑遍所有正整数,没问题。——约定1 ≤ a ≤ b ≤ c ≤ d ≤ 1000——这个a不是最小的。我就想看看最小的a,——就得动1000,动1000——电脑就罢工了。
Table[FindInstance[{a^3 + b^3 + c^3 - d^3 == n, 1 ≤ a ≤ b ≤ c ≤ d ≤ 1000}, {a, b, c, d}, Integers, 1], {n, 100}]
{{{a -> 4, b -> 4, c -> 6, d -> 7}}, {{a -> 1, b -> 1, c -> 1, d -> 1}}, {{a -> 15, b -> 385, c -> 499, d -> 566}}, {{a -> 1, b -> 4, c -> 4, d -> 5}}, {{a -> 5, b -> 524, c -> 530, d -> 664}},
{{a -> 2, b -> 5, c -> 6, d -> 7}}, {{a -> 2, b -> 6, c -> 8, d -> 9}}, {{a -> 1, b -> 32, c -> 104, d -> 105}}, {{a -> 1, b -> 2, c -> 3, d -> 3}}, {{a -> 3, b -> 103, c -> 111, d -> 135}},
{{a -> 1, b -> 130, c -> 141, d -> 171}}, {{a -> 1, b -> 297, c -> 619, d -> 641}}, {{a -> 1, b -> 7, c -> 10, d -> 11}}, {{a -> 5, b -> 296, c -> 881, d -> 892}}, {{a -> 2, b -> 32, c -> 104, d -> 105}},
{{a -> 2, b -> 2, c -> 3, d -> 3}}, {{a -> 3, b -> 3, c -> 3, d -> 4}}, {{a -> 1, b -> 25, c -> 50, d -> 52}}, {{a -> 1, b -> 75, c -> 215, d -> 218}}, {{a -> 1, b -> 26, c -> 76, d -> 77}},
{{a -> 1, b -> 21, c -> 55, d -> 56}}, {{a -> 1, b -> 28, c -> 85, d -> 86}}, {{a -> 2, b -> 23, c -> 44, d -> 46}}, {{a -> 5, b -> 167, c -> 621, d -> 625}}, {{a -> 1, b -> 8, c -> 8, d -> 10}},
{{a -> 2, b -> 75, c -> 215, d -> 218}}, {{a -> 1, b -> 87, c -> 468, d -> 469}}, {{a -> 1, b -> 3, c -> 3, d -> 3}}, {{a -> 1, b -> 13, c -> 14, d -> 17}}, {{a -> 1, b -> 13, c -> 18, d -> 20}},
{{a -> 58, b -> 511, c -> 667, d -> 755}}, {{a -> 2, b -> 8, c -> 8, d -> 10}}, {{a -> 5, b -> 5, c -> 8, d -> 9}}, {{a -> 2, b -> 87, c -> 468, d -> 469}}, {{a -> 2, b -> 3, c -> 3, d -> 3}},
{{a -> 2, b -> 13, c -> 14, d -> 17}}, {{a -> 1, b -> 40, c -> 71, d -> 75}}, {{a -> 1, b -> 37, c -> 50, d -> 56}}, {{a -> 1, b -> 16, c -> 25, d -> 27}}, {{a -> 7, b -> 241, c -> 532, d -> 548}},
{{a -> 17, b -> 17, c -> 23, d -> 28}}, {{a -> 2, b -> 5, c -> 5, d -> 6}}, {{a -> 4, b -> 11, c -> 14, d -> 16}}, {{a -> 1, b -> 8, c -> 12, d -> 13}}, {{a -> 2, b -> 37, c -> 50, d -> 56}},
{{a -> 1, b -> 256, c -> 533, d -> 552}}, {{a -> 1, b -> 19, c -> 26, d -> 29}}, {{a -> 1, b -> 6, c -> 7, d -> 8}}, {{a -> 4, b -> 262, c -> 265, d -> 332}}, {{a -> 23, b -> 29, c -> 77, d -> 79}},
{{a -> 2, b -> 8, c -> 12, d -> 13}}, {{a -> 1, b -> 602, c -> 659, d -> 796}}, {{a -> 2, b -> 256, c -> 533, d -> 552}}, {{a -> 3, b -> 3, c -> 3, d -> 3}}, {{a -> 1, b -> 192, c -> 353, d -> 371}},
{{a -> 1, b -> 62, c -> 103, d -> 110}}, {{a -> 1, b -> 31, c -> 42, d -> 47}}, {{a -> 1, b -> 25, c -> 34, d -> 38}}, {{a -> 2, b -> 602, c -> 659, d -> 796}}, {{a -> 5, b -> 348, c -> 770, d -> 793}},
{{a -> 2, b -> 80, c -> 237, d -> 240}}, {{a -> 1, b -> 668, c -> 845, d -> 966}}, {{a -> 1, b -> 22, c -> 41, d -> 43}}, {{a -> 1, b -> 102, c -> 146, d -> 161}}, {{a -> 1, b -> 4, c -> 8, d -> 8}},
{{a -> 1, b -> 85, c -> 91, d -> 111}}, {{a -> 4, b -> 4, c -> 4, d -> 5}}, {{a -> 5, b -> 95, c -> 185, d -> 193}}, {{a -> 2, b -> 668, c -> 845, d -> 966}}, {{a -> 1, b -> 95, c -> 377, d -> 379}},
{{a -> 1, b -> 11, c -> 20, d -> 21}}, {{a -> 2, b -> 4, c -> 4, d -> 4}}, {{a -> 1, b -> 7, c -> 9, d -> 10}}, {{a -> 1, b -> 29, c -> 43, d -> 47}}, {{a -> 4, b -> 297, c -> 619, d -> 641}},
{{a -> 4, b -> 7, c -> 10, d -> 11}}, {{a -> 2, b -> 95, c -> 377, d -> 379}}, {{a -> 2, b -> 11, c -> 20, d -> 21}}, {{a -> 1, b -> 26, c -> 53, d -> 55}}, {{a -> 2, b -> 7, c -> 9, d -> 10}},
{{a -> 1, b -> 260, c -> 282, d -> 342}}, {{a -> 1, b -> 12, c -> 12, d -> 15}}, {{a -> 3, b -> 31, c -> 42, d -> 47}}, {{a -> 1, b -> 22, c -> 24, d -> 29}}, {{a -> 4, b -> 28, c -> 85, d -> 86}},
{{a -> 2, b -> 26, c -> 53, d -> 55}}, {{a -> 8, b -> 14, c -> 32, d -> 33}}, {{a -> 2, b -> 260, c -> 282, d -> 342}}, {{a -> 2, b -> 12, c -> 12, d -> 15}}, {{a -> 1, b -> 6, c -> 6, d -> 7}},
{{a -> 1, b -> 13, c -> 26, d -> 27}}, {{a -> 1, b -> 192, c -> 364, d -> 381}}, {{a -> 4, b -> 13, c -> 18, d -> 20}}, {{a -> 31, b -> 94, c -> 535, d -> 536}}, {{a -> 20, b -> 38, c -> 38, d -> 49}},
{{a -> 3, b -> 95, c -> 377, d -> 379}}, {{a -> 1, b -> 14, c -> 20, d -> 22}}, {{a -> 1, b -> 17, c -> 18, d -> 22}}, {{a -> 1, b -> 9, c -> 14, d -> 15}}, {{a -> 1, b -> 16, c -> 36, d -> 37}}}
ParallelTable[a /. First@FindInstance[{a^3 + b^3 + c^3 - d^3 == n, 1 ≤ a ≤ b ≤ c ≤ d ≤ 1000}, {a, b, c, d}, Integers, 1], {n, 1000}]
4, 1, 15, 1, 5, 2, 2, 1, 1, 3, 1, 1, 1, 5, 2, 2, 3, 1, 1, 1, 1, 1, 2, 5, 1, 2, 1, 1, 1, 1, 58, 2, 5, 2, 2, 2, 1, 1, 1, 7, 17, 2, 4, 1, 2, 1, 1, 1, 4, 23, 2, 1, 2, 3, 1, 1, 1, 1, 2, 5, 2, 1, 1, 1, 1, 1, 4, 5, 2, 1, 1, 2, 1, 1, 4, 4, 2, 2,
1, 2, 1, 1, 3, 1, 4, 2, 8, 2, 2, 1, 1, 1, 4, 31, 20, 3, 1, 1, 1, 1, 4, 1, 1, 2, 2, 2, 1, 3, 2, 1, 4, 10, 11, 2, 4, 1, 2, 3, 1, 4, 1, 26, 2, 3, 3, 1, 1, 4, 3, 1, 26, 5, 2, 1, 1, 3, 1, 7, 7, 5, 2, 1, 5, 2, 1, 5, 1, 16, 2, 11, 1, 1, 1, 1,
1, 1, 13, 2, 2, 1, 1, 1, 2, 12, 4, 4, 2, 2, 1, 4, 1, 1, 3, 7, 1, 2, 3, 2, 2, 1, 3, 1, 1, 1, 17, 3, 2, 1, 2, 1, 1, 1, 1, 5, 2, 5, 2, 1, 1, 1, 1, 1, 5, 9, 8, 2, 1, 1, 1, 1, 70, 74, 14, 2, 2, 1, 1, 1, 1, 7, 5, 5, 1, 1, 1, 1, 1, 3, 10, 2, 2,
2, 1, 2, 1, 1, 6, 4, 23, 2, 8, 1, 1, 3, 1, 1, 1, 26, 2, 2, 3, 1, 1, 1, 4, 4, 8, 5, 2, 1, 1, 1, 4, 1, 4, 5, 2, 2, 2, 4, 1, 3, 1, 7, 5, 5, 5, 2, 1, 1, 1, 1, 10, 5, 5, 2, 1, 1, 1, 3, 9, 13, 5, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 4,
4, 2, 2, 3, 2, 2, 1, 1, 6, 13, 20, 3, 3, 1, 1, 1, 3, 3, 7, 8, 2, 1, 2, 1, 1, 1, 1, 1, 2, 21, 1, 2, 1, 1, 1, 1, 10, 2, 5, 2, 1, 1, 1, 7, 7, 7, 23, 2, 2, 1, 1, 3, 1, 1, 4, 8, 2, 2, 3, 1, 1, 1, 7, 1, 8, 6, 1, 1, 1, 4, 2, 7, 1, 2, 2, 2, 3, 4,
1, 2, 1, 13, 8, 8, 1, 2, 3, 1, 4, 1, 4, 2, 3, 3, 2, 1, 1, 1, 1, 10, 35, 5, 1, 1, 1, 1, 3, 6, 1, 2, 2, 2, 1, 3, 1, 1, 4, 28, 5, 2, 1, 1, 1, 1, 1, 9, 4, 2, 2, 2, 2, 1, 1, 1, 3, 4, 20, 5, 2, 1, 1, 1, 7, 4, 1, 5, 2, 1, 1, 1, 1, 2, 1, 7, 2, 2,
1, 1, 1, 1, 1, 4, 7, 2, 2, 2, 1, 1, 1, 6, 1, 4, 11, 2, 2, 1, 3, 1, 3, 1, 1, 8, 2, 3, 1, 1, 1, 1, 1, 16, 5, 2, 2, 2, 1, 1, 1, 10, 10, 11, 6, 1, 1, 1, 1, 1, 3, 4, 2, 2, 2, 1, 1, 3, 1, 1, 1, 8, 2, 1, 3, 2, 1, 1, 1, 7, 8, 3, 1, 2, 1, 1, 1, 4,
7, 2, 5, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 2, 1, 1, 10, 8, 3, 2, 1, 1, 1, 1, 1, 1, 17, 2, 1, 2, 1, 1, 2, 1, 16, 2, 5, 1, 2, 1, 2, 3, 1, 4, 2, 5, 2, 1, 3, 1, 1, 3, 31, 20, 2, 4, 1, 2, 1, 1, 7, 31, 8, 2, 4, 1, 1, 1, 3, 4, 4, 11, 2, 2, 1,
1, 3, 1, 1, 1, 14, 2, 2, 4, 1, 1, 1, 1, 4, 5, 5, 2, 1, 1, 1, 1, 4, 7, 17, 2, 2, 2, 2, 1, 1, 3, 13, 5, 11, 11, 1, 1, 1, 1, 1, 10, 5, 2, 2, 1, 1, 1, 1, 6, 1, 5, 2, 2, 1, 1, 1, 2, 7, 1, 8, 2, 2, 2, 1, 1, 1, 4, 1, 41, 5, 2, 1, 1, 1, 1, 3, 10,
5, 2, 1, 1, 1, 1, 1, 3, 10, 2, 2, 2, 2, 1, 1, 1, 1, 1, 11, 5, 2, 2, 2, 1, 1, 1, 1, 26, 3, 3, 1, 1, 1, 2, 7, 4, 8, 2, 2, 1, 1, 3, 1, 1, 4, 14, 2, 2, 8, 1, 2, 1, 1, 4, 14, 6, 2, 3, 1, 1, 1, 13, 1, 17, 5, 2, 1, 1, 3, 1, 6, 1, 11, 2, 1, 3, 1,
1, 1, 1, 4, 2, 5, 2, 2, 2, 1, 1, 3, 4, 11, 5, 3, 2, 1, 1, 1, 3, 7, 20, 3, 1, 1, 2, 1, 3, 4, 13, 2, 8, 5, 1, 1, 1, 1, 4, 16, 8, 2, 1, 2, 1, 3, 1, 1, 4, 2, 3, 1, 4, 1, 2, 4, 7, 4, 2, 8, 2, 3, 1, 1, 4, 4, 10, 8, 3, 2, 2, 1, 1, 3, 1, 28, 8, 3,
1, 1, 1, 1, 1, 1, 10, 2, 2, 2, 1, 1, 1, 1, 7, 7, 14, 2, 2, 1, 1, 4, 1, 1, 10, 53, 2, 2, 3, 1, 1, 1, 4, 13, 8, 5, 2, 1, 1, 3, 1, 1, 7, 5, 2, 2, 3, 1, 2, 3, 1, 22, 8, 11, 2, 1, 3, 1, 7, 1, 7, 23, 2, 3, 1, 1, 1, 1, 1, 19, 5, 2, 2, 1, 1, 1, 3,
1, 1, 14, 2, 2, 1, 3, 1, 1, 1, 25, 5, 2, 3, 1, 1, 2, 1, 12, 22, 5, 2, 2, 3, 1, 1, 3, 3, 25, 14, 8, 1, 2, 1, 1, 3, 1, 7, 2, 8, 2, 1, 6, 1, 1, 1, 28, 5, 2, 5, 1, 1, 1, 4, 4, 10, 35, 2, 1, 1, 1, 1, 1, 1, 4, 2, 2, 2, 1, 2, 1} |