#lang racket ; Returns the sum of the digits of integer n. (define (sum-digits n) ; Returns n!. (define (factorial n) ; Returns the nth number in the Fibonacci series. (define (fib n) ; Returns #t if n is prime and #f otherwise. ; The first function shown is a helper function. (define (prime?-help n i) (define (prime? n) (prime?-help n 2))