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(use-modules (srfi srfi-1))
(define (divisible? m n)
(zero? (modulo m n)))
(define (prime-sieve n)
(define (mark-multiples! bits x)
(define (mark y)
(when (< y n)
(bitvector-set! bits (1- y) #t)
(mark (+ y x))))
(mark x))
(define (sieve m primes bits)
(cond ((= m n)
primes)
((bitvector-ref bits (1- m))
(sieve (1+ m) primes bits))
(else
(mark-multiples! bits m)
(sieve (1+ m) (cons m primes) bits))))
(sieve 2 '() (make-bitvector n)))
(reduce + 0 (prime-sieve 2000000))
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