; hamming numbers
(define (hamming n)
(let ((aq (make-vector (+ n 1) 0))
(i2 1) (i3 1) (i5 1) (x2 2) (x3 3) (x5 5))
(vector-set! aq 1 1)
(do ((h 2 (+ h 1))) ((< n h) aq)
(let ((t (min x2 x3 x5)))
(vector-set! aq h t)
(when (= x2 t)
(set! i2 (+ i2 1))
(set! x2 (* 2 (vector-ref aq i2))))
(when (= x3 t)
(set! i3 (+ i3 1))
(set! x3 (* 3 (vector-ref aq i3))))
(when (= x5 t)
(set! i5 (+ i5 1))
(set! x5 (* 5 (vector-ref aq i5))))))))
(define (nth-hamming n) (vector-ref (hamming n) n))
(define h1000 (hamming 1000))
(do ((i 1 (+ i 1))) ((< 1000 i))
(display i) (display #\tab)
(display (vector-ref h1000 i))
(newline))
(newline)
(display (nth-hamming 1000000)) (newline)
programmingpraxis
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