(* Question 2 *)let val p n =  if p<2 or n<2 then failwith "argument(s) incorrect(s)" else  let rec aux r = function   | v when v mod p = 0 -> aux (r+1) (v/p)   | _ -> r  in aux 0 n ;; (* Question 3 *)let ppdiv d n =  if n<=0 or d<=0 or d>n then failwith "arguments incorrects" ;  let rec aux k = function   | n when n mod k = 0 -> k   | n -> aux (k+1) n  in aux d n ;;(* Question 4 *)let rec puiss n = function  | 0 -> 1  | e -> n * (puiss n (e-1)) ;;(* Question 5 *)let factorise n =  let rec aux p dec = function   | 1 -> dec   | v -> let p' = ppdiv p v in let q = val p' v in     let v' = (v/(puiss p' q)) in aux (p'+1) ((p',q)::dec) v'  in aux 2 [] n ;;(* Question 6 *)let est_premier n = match factorise n with  | [(_,1)] -> true  | _ -> false ;; (* Question 6 *)let rec next_prime n = match est_premier n with  | true -> n  | false -> next_prime (n+1) ;; (* Question 7 *)let premiers_depuis n q =  let rec aux n' r = function   | 0 -> r   | k -> let n' = next_prime n' in aux (n'+1) (n'::r) (k-1)  in aux n [] q ;; let rec premiers_depuis n = function   | 0 -> []   | k when est_premier n -> n::(premiers_depuis (n+1) (k-1))   | k -> premiers_depuis (n+1) k ;;