[中譯] ProjectEuler 383 Divisibility comparison between factori
看板puzzle (益智遊戲 - 數獨,拼圖,推理,西洋棋)作者LPH66 (-858993460)時間13年前 (2012/05/07 03:10)推噓1(1推 0噓 0→)留言1則, 1人參與討論串1/1
383. Divisibility comparison between factorials
http://projecteuler.net/problem=383
令 f_5(n) 表示最大的整數 x 使 5^x 能整除 n。
例如 f_5(625000) = 7.
令 T_5(n) 表示滿足 f_5((2*i-1)!) < 2*f_5(i!) 且 1≦i≦n 的 i 的個數。
可以驗證 T_5(10^3) = 68 and T_5(10^9) = 2408210。
求 T_5(10^18)。
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