Add A001146 Number of Boolean Functions sequence (TheAlgorithms#297)

OleksiiHe · web-flow · commit 1c465ecd2cc7 · 2022-03-01T17:05:41.000+02:00
diff --git a/Algorithms.Tests/Sequences/NumberOfBooleanFunctionsSequenceTests.cs b/Algorithms.Tests/Sequences/NumberOfBooleanFunctionsSequenceTests.cs
@@ -0,0 +1,19 @@
+﻿using System.Linq;
+using System.Numerics;
+using Algorithms.Sequences;
+using FluentAssertions;
+using NUnit.Framework;
+
+namespace Algorithms.Tests.Sequences
+{
+    public class NumberOfBooleanFunctionsSequenceTests
+    {
+        [Test]
+        public void First5ElementsCorrect()
+        {
+            var sequence = new NumberOfBooleanFunctionsSequence().Sequence.Take(5);
+            sequence.SequenceEqual(new BigInteger[] { 2, 4, 16, 256, 65536 })
+                .Should().BeTrue();
+        }
+    }
+}
diff --git a/Algorithms/Sequences/NumberOfBooleanFunctionsSequence.cs b/Algorithms/Sequences/NumberOfBooleanFunctionsSequence.cs
@@ -0,0 +1,37 @@
+﻿using System.Collections.Generic;
+using System.Numerics;
+
+namespace Algorithms.Sequences
+{
+    /// <summary>
+    ///     <para>
+    ///         Sequence of number of truth tables generated by Boolean expressions of n variables
+    ///         (Double exponentials of 2: a(n) = 2^(2^n)).
+    ///     </para>
+    ///     <para>
+    ///         Wikipedia: https://wikipedia.org/wiki/Truth_table.
+    ///     </para>
+    ///     <para>
+    ///         OEIS: https://oeis.org/A001146.
+    ///     </para>
+    /// </summary>
+    public class NumberOfBooleanFunctionsSequence : ISequence
+    {
+        /// <summary>
+        /// Gets sequence of number Of Boolean functions.
+        /// </summary>
+        public IEnumerable<BigInteger> Sequence
+        {
+            get
+            {
+                var n = new BigInteger(2);
+
+                while (true)
+                {
+                    yield return n;
+                    n *= n;
+                }
+            }
+        }
+    }
+}
diff --git a/README.md b/README.md
@@ -108,6 +108,7 @@ This repository contains algorithms and data structures implemented in C# for ed
     * [A000290 Squares](./Algorithms/Sequences/SquaresSequence.cs)
     * [A000578 Cubes](./Algorithms/Sequences/CubesSequence.cs)
     * [A000720 PrimePi](./Algorithms/Sequences/PrimePiSequence.cs)
+    * [A001146 Number of Boolean Functions](./Algorithms/Sequences/NumberOfBooleanFunctionsSequence.cs)
     * [A001462 Golomb's](./Algorithms/Sequences/GolombsSequence.cs)
     * [A001478 Negative Integers](./Algorithms/Sequences/NegativeIntegersSequence.cs)
     * [A002110 Primorial Numbers](./Algorithms/Sequences/PrimorialNumbersSequence.cs)
