Attractive numbers: Difference between revisions
Added Common Lisp
Not a robot (talk | contribs) (Add PL/I) |
(Added Common Lisp) |
||
Line 821:
92 93 94 95 98 99 102 105 106 108 110 111 112 114 115 116 117 118
119 120</pre>
=={{header|Common Lisp}}==
<lang Lisp>
(defun attractivep (n)
(primep (length (factors n))) )
; For primality testing we can use different methods, but since we have to define factors that's what we'll use
(defun primep (n)
(= (length (factors n)) 1) )
(defun factors (n)
"Return a list of factors of N."
(when (> n 1)
(loop with max-d = (isqrt n)
for d = 2 then (if (evenp d) (+ d 1) (+ d 2)) do
(cond ((> d max-d) (return (list n))) ; n is prime
((zerop (rem n d)) (return (cons d (factors (truncate n d)))))))))
</lang>
{{out}}
<pre>(dotimes (i 121) (when (attractivep i) (princ i) (princ " ")))
4 6 8 9 10 12 14 15 18 20 21 22 25 26 27 28 30 32 33 34 35 38 39 42 44 45 46 48 49 50 51 52 55 57 58 62 63 65 66 68 69 70 72 74 75 76 77 78 80 82 85 86 87 91 92 93 94 95 98 99 102 105 106 108 110 111 112 114 115 116 117 118 119 120</pre>
=={{header|Cowgol}}==
| |||