Find squares n where n+1 is prime: Difference between revisions
added racket example
Thundergnat (talk | contribs) m (syntax highlighting fixup automation) |
Dr-neptune (talk | contribs) (added racket example) |
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done...
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=={{header|Racket}}==
<syntaxhighlight lang="racket">
#lang racket
(require racket)
(define (find-subprime-squares up-to)
(let rc ([curr-num 1]
[found '()])
(let ([n-sq (* curr-num curr-num)])
(cond [(>= n-sq up-to) (reverse found)]
[(prime? (add1 n-sq)) (rc (add1 curr-num) (cons n-sq found))]
[else (rc (add1 curr-num) found)]))))
(define (prime? n)
(let iter ([counter 2])
(cond [(eq? n 1) #f]
[(<= (expt counter 2) n)
(if (zero? (remainder n counter))
#f
(iter (add1 counter)))]
[else #t])))
(find-subprime-squares 1000)
</syntaxhighlight>
{{out}}
<pre>
'(1 4 16 36 100 196 256 400 576 676)
</pre>
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