Problem 164

题目发布于 2007-10-20 翻译更新于 2015-10-20

Numbers for which no three consecutive digits have a sum greater than a given value

How many 20 digit numbers n (without any leading zero) exist such that no three consecutive digits of n have a sum greater than 9?

没有连续三位数字的和超过给定值的数

有多少个20位数字n（不包括前导0）满足，不存在连续三位数字的和超过9？