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连续数的积 + 连续数的积 ≡ 连续数的积。——还是无限数字串!——想通了。答案挺多的!——随便来一个!!
\(4×5×6×7+5×6×7×8=3×4×5×6×7\)
\(5×6×\cdots×14+6×7×\cdots×15=4×5×\cdots×14\)
\(6×7×\cdots×23+7×8×\cdots×24=5×6×\cdots×23\)
\(7×8×\cdots×34+8×9×\cdots×35=6×7×\cdots×34\)
\(8×9×\cdots×47+9×10×\cdots×48=7×8×\cdots×47\)
\(9×10×\cdots×62+10×11×\cdots×63=8×9×\cdots×62\)
{7, 14, 23, 34, 47, 62, 79, 98, 119, 142, 167, 194, 223, 254, 287, 322, 359, 398, 439, 482}——最后一个数。
\(\displaystyle\prod_{k=n+1}^{n^2-2}+\prod_{k=n+2}^{n^2-1}≡\prod_{k=n}^{n^2-2}\) |
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