[理工] [離散]-排列組合
A palindrome is a word that reads the same forward or backward.How many
seven-letter palindromes can be made out of the English alphabt?
這題覺得答案怪怪的,答案是26^4
但,不是只要決定前面3個字母排即可?也就是1與7同,2與6同,3與5同,這樣
不是應該是26^3?謝謝。
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