Unformatted text preview: a n . Problem 3: Find the number of non-negative integers less than 1,000,000 whose digits sum up to no more than 23. Problem 4: We call an n-digit number valid if it contains an even number of 0s. Let a n be the number of valid n-digit numbers. (a) Find a recurrence relation for a n . (b) Use generating functions to ﬁnd an explicit formula for a n . 1...
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- Spring '09
- Math, Negative and non-negative numbers, Recurrence relation, Generating function, valid n-digit numbers