WITH RECURSIVE asd (i) AS
(
  SELECT 1
  UNION ALL
  SELECT i + 1 FROM asd WHERE i < 1000
)
SELECT GROUP_CONCAT(num1.i SEPARATOR '&') 
FROM asd num1
WHERE num1.i > 1
    AND num1.i NOT IN (
SELECT asd.i FROM asd INNER JOIN asd AS num1 
WHERE asd.i > num1.i 
    AND asd.i % num1.i = 0
    AND num1.i != 1)