Data commit

Task/Totient-function/Racket/totient-function.rkt

@@ -0,0 +1,18 @@
+#lang racket
+
+(require math/number-theory)
+
+(define (prime*? n) (= (totient n) (sub1 n)))
+
+(for ([n (in-range 1 26)])
+  (printf "φ(~a) = ~a~a~a\n"
+          n
+          (totient n)
+          (if (prime*? n) " is prime" "")
+          (if (prime? n) " (confirmed)" "")))
+
+(for/fold ([count 0] #:result (void)) ([n (in-range 1 10001)])
+   (define new-count (if (prime*? n) (add1 count) count))
+   (when (member n '(100 1000 10000))
+     (printf "Primes up to ~a: ~a\n" n new-count))
+   new-count)