Pell numbers: Difference between revisions
→{{header|Common Lisp}}
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(recurrent-sequence-2 2 2 2 1 max) )
(defun fibonacci-sequence (max) ; As an extra
(recurrent-sequence-2 1 1 1 1 max) )
(defun rational-approximation-sqrt2 (max)
"Approximate square root of 2 with (P(n-1)+P(n-2))/P(n)"
(butlast (maplist #'(lambda (l) (/ (+ (first l) (or (second l) 0)) (or (second l) 1))) (pell-sequence max))) )
(defun pell-primes (max)
(do* ((i 0 (1+ i))
(result (list 1 0))
(b0 0 b1)
(b1 1 b2)
(b2 (+ (* 2 b1) (* 1 b0)) (+ (* 2 b1) (* 1 b0))) )
((> (length result) max) (nreverse result))
; primep can be any function determining whether a number is prime, for example,
; https://rosettacode.org/wiki/Primality_by_Wilson%27s_theorem#Common_Lisp
(when (primep b2)
(push b2 result) )))
</syntaxhighlight>
Line 152 ⟶ 163:
</syntaxhighlight>
First 7 Pell primes:
<syntaxhighlight lang="CommonLisp">
(pell-primes 7)
(0 1 2 5 29 5741 33461 44560482149)
</syntaxhighlight>
Still missing some of the taks
=={{header|FreeBASIC}}==
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