Combinatorics problem! (Probably easy)

Find the number of ways in which we can select three integers from the set of integers, $$\{1,2,3,4,5,6,7,................,47,48,49\}$$ such that no two are consecutive

$$Bonus$$: Prove this for selecting $$r$$ integers from first $$n$$ natural numbers such that no two are consecutive.

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