Lisp - prime number

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I am trying to learn lisp and I have some difficulties with prime numbers. I need a function is-prime and if it is prime I have to return t and if it is not I have to return nil.

(prime 41) => t

(prime 35) => nil

So far I've got:

(defun is-prime (n d) 
  (if (= d 1) 
      (print "t") 
      (if (= (% n d) 0) 
          (print "nil") 
          (is-prime (n (- d 1) )))))

but I have 2 parameters there and I have no idea how to use only one. Plus, it's not working at all. Can anyone help me with this? Thanks!

3 Answers
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