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Task/Semiprime/EchoLisp/semiprime.echolisp

@@ -0,0 +1,20 @@
+(lib 'math)
+(define (semi-prime? n)
+   (= (length (prime-factors n)) 2))
+
+(for ((i 100))
+    (when (semi-prime? i) (write i)))
+
+4 6 9 10 14 15 21 22 25 26 33 34 35 38 39 46 49 51 55 57 58 62 65 69 74 77 82 85 86 87 91 93 94 95
+
+(lib 'bigint)
+(define N (* (random-prime 10000000) (random-prime 10000000)))
+   → 6764578882969
+(semi-prime? N)
+    → #t
+
+;; a pair n,n+1 of semi-primes
+(prime-factors 100000000041)
+    → (3 33333333347)
+(prime-factors 100000000042)
+    → (2 50000000021)