Larger Digit Permutation
For a positive integer define to be the number of strictly larger integers which can be formed by permuting the digits of .
Leading zeros are not allowed and so for the total list of permutations would be:
giving .
Further define to be the sum of for all -digit numbers . You are given .
Find .
更大的数字重排(一)
对于正整数,定义为对的数字进行重排所能得到的严格大于的整数数量。
重排不允许有前导零,因此对于,所有的合法重排包括:
因此可得。
再定义为所有的位整数对应的之和。已知。
求。
Gitalking ...