Pell numbers: Difference between revisions

Content added Content deleted
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(do* ((i 0 (1+ i))
(do* ((i 0 (1+ i))
(result (list 1 0))
(result (list 1 0))
(indices nil)
(b0 0 b1)
(b0 0 b1)
(b1 1 b2)
(b1 1 b2)
(b2 (+ (* 2 b1) (* 1 b0)) (+ (* 2 b1) (* 1 b0))) )
(b2 (+ (* 2 b1) (* 1 b0)) (+ (* 2 b1) (* 1 b0))) )
((> (length result) max) (nreverse result))
((> (length result) max) (values (nreverse result)(nreverse indices)))
; primep can be any function determining whether a number is prime, for example,
; primep can be any function determining whether a number is prime, for example,
; https://rosettacode.org/wiki/Primality_by_Wilson%27s_theorem#Common_Lisp
; https://rosettacode.org/wiki/Primality_by_Wilson%27s_theorem#Common_Lisp
(when (primep b2)
(when (primep b2)
(push b2 result) )))
(push b2 result)
(push i indices) )))


</syntaxhighlight>
</syntaxhighlight>
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</syntaxhighlight>
</syntaxhighlight>


First 7 Pell primes:
First 7 Pell primes and, as second value, the corresponding indices:
<syntaxhighlight lang="CommonLisp">
<syntaxhighlight lang="CommonLisp">
(pell-primes 7)
(pell-primes 7)
(0 1 2 5 29 5741 33461 44560482149)
(0 1 2 5 29 5741 33461 44560482149) ;
(0 1 3 9 11 27)
</syntaxhighlight>
</syntaxhighlight>


Still missing some of the taks
Still missing some of the taks
Retrieved from "https://rosettacode.org/wiki/Pell_numbers"