F# Map Reduce

let nums =[|1..100|]

let sqr x = x*x

let sumofsqr nums =
    let mutable acc=0
    for n in nums do
        acc<-acc+sqr n
    acc

let rec sumofsqrRec nums=
    match nums with
    | []-> 0
    |  n::rest -> (sqr n)+ (sumofsqrRec rest ) 

let rec sumofsqrPipe nums=
    nums
    |>Seq.map sqr   
    |>Seq.sum