Add A006862 Euclid Numbers sequence (TheAlgorithms#295)

OleksiiHe · web-flow · commit e4e4cd3fdb28 · 2022-02-27T12:00:16.000+02:00
diff --git a/Algorithms.Tests/Sequences/EuclidNumbersSequenceTests.cs b/Algorithms.Tests/Sequences/EuclidNumbersSequenceTests.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 EuclidNumbersSequenceTests
+    {
+        [Test]
+        public void First10ElementsCorrect()
+        {
+            var sequence = new EuclidNumbersSequence().Sequence.Take(10);
+            sequence.SequenceEqual(new BigInteger[] 
+                { 2, 3, 7, 31, 211, 2311, 30031, 510511, 9699691, 223092871 })
+                .Should().BeTrue();
+        }
+    }
+}
diff --git a/Algorithms/Sequences/EuclidNumbersSequence.cs b/Algorithms/Sequences/EuclidNumbersSequence.cs
@@ -0,0 +1,35 @@
+using System.Collections.Generic;
+using System.Numerics;
+
+namespace Algorithms.Sequences
+{
+    /// <summary>
+    ///     <para>
+    ///         Sequence of Euclid numbers: 1 + product of the first n primes.
+    ///     </para>
+    ///     <para>
+    ///         Wikipedia: https://wikipedia.org/wiki/Euclid_number.
+    ///     </para>
+    ///     <para>
+    ///         OEIS: https://oeis.org/A006862.
+    ///     </para>
+    /// </summary>
+    public class EuclidNumbersSequence : ISequence
+    {
+        /// <summary>
+        /// Gets sequence of Euclid numbers.
+        /// </summary>
+        public IEnumerable<BigInteger> Sequence
+        {
+            get
+            {
+                var primorialNumbers = new PrimorialNumbersSequence().Sequence;
+
+                foreach (var n in primorialNumbers)
+                {
+                    yield return n + 1;
+                }
+            }
+        }
+    }
+}
diff --git a/README.md b/README.md
@@ -111,6 +111,7 @@ This repository contains algorithms and data structures implemented in C# for ed
     * [A001478 Negative Integers](./Algorithms/Sequences/NegativeIntegersSequence.cs)
     * [A002110 Primorial Numbers](./Algorithms/Sequences/PrimorialNumbersSequence.cs)
     * [A005132 Recaman's](./Algorithms/Sequences/RecamansSequence.cs)
+    * [A006862 Euclid Numbers](./Algorithms/Sequences/EuclidNumbersSequence.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)
     * [A007318 Binomial](./Algorithms/Sequences/BinomialSequence.cs)
