Add A002110 Primorial Numbers sequence (TheAlgorithms#294)

OleksiiHe · web-flow · commit 4336bed7fa31 · 2022-02-25T14:53:53.000+02:00
diff --git a/Algorithms.Tests/Sequences/PrimorialNumbersSequenceTests.cs b/Algorithms.Tests/Sequences/PrimorialNumbersSequenceTests.cs
@@ -0,0 +1,20 @@
+﻿using System.Linq;
+using System.Numerics;
+using Algorithms.Sequences;
+using FluentAssertions;
+using NUnit.Framework;
+
+namespace Algorithms.Tests.Sequences
+{
+    public class PrimorialNumbersSequenceTests
+    {
+        [Test]
+        public void First10ElementsCorrect()
+        {
+            var sequence = new PrimorialNumbersSequence().Sequence.Take(10);
+            sequence.SequenceEqual(new BigInteger[] 
+                { 1, 2, 6, 30, 210, 2310, 30030, 510510, 9699690, 223092870 })
+                .Should().BeTrue();
+        }
+    }
+}
diff --git a/Algorithms/Sequences/PrimorialNumbersSequence.cs b/Algorithms/Sequences/PrimorialNumbersSequence.cs
@@ -0,0 +1,37 @@
+using System.Collections.Generic;
+using System.Numerics;
+
+namespace Algorithms.Sequences
+{
+    /// <summary>
+    ///     <para>
+    ///         Sequence of primorial numbers: product of first n primes.
+    ///     </para>
+    ///     <para>
+    ///         Wikipedia: https://wikipedia.org/wiki/Primorial.
+    ///     </para>
+    ///     <para>
+    ///         OEIS: https://oeis.org/A002110.
+    ///     </para>
+    /// </summary>
+    public class PrimorialNumbersSequence : ISequence
+    {
+        /// <summary>
+        /// Gets sequence of primorial numbers.
+        /// </summary>
+        public IEnumerable<BigInteger> Sequence
+        {
+            get
+            {
+                var primes = new PrimesSequence().Sequence;
+                var n = new BigInteger(1);
+
+                foreach (var p in primes)
+                {
+                    yield return n;
+                    n *= p;
+                }
+            }
+        }
+    }
+}
diff --git a/README.md b/README.md
@@ -109,6 +109,7 @@ This repository contains algorithms and data structures implemented in C# for ed
     * [A000720 PrimePi](./Algorithms/Sequences/PrimePiSequence.cs)
     * [A001462 Golomb's](./Algorithms/Sequences/GolombsSequence.cs)
     * [A001478 Negative Integers](./Algorithms/Sequences/NegativeIntegersSequence.cs)
+    * [A002110 Primorial Numbers](./Algorithms/Sequences/PrimorialNumbersSequence.cs)
     * [A005132 Recaman's](./Algorithms/Sequences/RecamansSequence.cs)
     * [A006879 Number of Primes by Number of Digits](./Algorithms/Sequences/NumberOfPrimesByNumberOfDigitsSequence.cs)
     * [A006880 Number of Primes by Powers of 10](./Algorithms/Sequences/NumberOfPrimesByPowersOf10Sequence.cs)
