Additive primes: Difference between revisions

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@@ Line 627: / Line 627: @@
 def prime?(n) # P3 Prime Generator primality test
-  return false unless n > 1 && 6.gcd(n % 6) == 1 || [2, 3].includes?(n)
+  return false unless (n | 1 == 3 if n < 5) || n.gcd(6) == 1
+  pc = typeof(n).new(5)
-  sqrt_n = Math.isqrt(n)  # For Crystal < 1.2.0 use Math.sqrt(n).to_i
+  while pc <= Math.isqrt(n)  # For Crystal < 1.2.0 use Math.sqrt(n).to_i
-  p = -1
+    return false if n % pc == 0 || n % (pc + 2) == 0
-  while (p += 6) <= sqrt_n
+    pc += 6
-    return false if n % p == 0 || n % (p + 2) == 0
   end
   true