Data commit

Task/Circular-primes/Julia/circular-primes.julia

@@ -0,0 +1,20 @@
+using Lazy, Primes
+
+function iscircularprime(n)
+    !isprime(n) && return false
+    dig = digits(n)
+    return all(i -> (m = evalpoly(10, circshift(dig, i))) >= n && isprime(m), 1:length(dig)-1)
+end
+
+filtcircular(n, rang) = Int.(collect(take(n, filter(iscircularprime, rang))))
+isprimerepunit(n) = isprime(evalpoly(BigInt(10), ones(Int, n)))
+filtrep(n, rang) = collect(take(n, filter(isprimerepunit, rang)))
+
+println("The first 19 circular primes are:\n", filtcircular(19, Lazy.range(2)))
+print("\nThe next 4 circular primes, in repunit format, are: ",
+    mapreduce(n -> "R($n) ", *, filtrep(4, Lazy.range(6))))
+
+println("\n\nChecking larger repunits:")
+for i in [5003, 9887, 15073, 25031, 35317, 49081]
+    println("R($i) is ", isprimerepunit(i) ? "prime." : "not prime.")
+end