Initial data commit

Task/Circular-primes/Factor/circular-primes.factor

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+USING: combinators.short-circuit formatting io kernel lists
+lists.lazy math math.combinatorics math.functions math.parser
+math.primes sequences sequences.extras ;
+
+! Create an ordered infinite lazy list of circular prime
+! "candidates" -- the numbers 2, 3, 5 followed by numbers
+! composed of only the digits 1, 3, 7, and 9.
+
+: candidates ( -- list )
+    L{ "2" "3" "5" "7" } 2 lfrom
+    [ "1379" swap selections >list ] lmap-lazy lconcat lappend ;
+
+: circular-prime? ( str -- ? )
+    all-rotations {
+        [ [ infimum ] [ first = ] bi ]
+        [ [ string>number prime? ] all? ]
+    } 1&& ;
+
+: circular-primes ( -- list )
+    candidates [ circular-prime? ] lfilter ;
+
+: prime-repunits ( -- list )
+    7 lfrom [ 10^ 1 - 9 / prime? ] lfilter ;
+
+"The first 19 circular primes are:" print
+19 circular-primes ltake [ write bl ] leach nl nl
+
+"The next 4 circular primes, in repunit format, are:" print
+4 prime-repunits ltake [ "R(%d) " printf ] leach nl