F# is the kind of language that can really energize someone who is excited about just sitting down and powering out a solution.
Here is an example of how to sum some fibonacci numbers.
let rec fibonacci n =
if n < 2 then 1
else fibonacci (n-2) + fibonacci(n-1)
//create a recursive function called fibonacci
//that takes the parameter n
// if n < 2 then 1 so this is the base case.
//else fib (n – 2) + fib (n – 1)
printfn "fibonacci = %A" (fibonacci 10)