An abstraction for easy Arithmetic and Geometric Progression creation in C#;

Sequence.cs

using System;
using System.Collections;
using System.Collections.Generic;

namespace Streamable
{
    public class Sequence<T> : IEnumerable<T>, IEnumerator<T>
    {
        private readonly Func<T, ulong, (T nextElement, bool isLast)> formulae;
        private readonly T firstElement;
        private bool isEnded;
        private ulong index;

        public Sequence(
            Func<T, ulong, (T nextElement, bool isLast)> formulae, 
            T firstElement)
        {
            this.formulae = formulae;
            this.firstElement = firstElement;

            this.isEnded = false;
            this.index = 0;
            this.Current = this.firstElement;
        }

        #region IEnumerable
        public T Current
        {
            get;
            private set;
        }

        object IEnumerator.Current => this.Current;

        private readonly object valueGate = new();
        public bool MoveNext()
        {
            lock(valueGate)
            {
                if (isEnded)
                {
                    return false;
                }
                
                this.index++;
                (Current, isEnded) = formulae(Current, this.index);
            }
            return true;
        }

        public void Reset()
        {
            lock(valueGate)
            {
                this.isEnded = false;
                this.index = 0;
                this.Current = this.firstElement;
            }
        }
        #endregion

        #region IEnumerable
        public IEnumerator<T> GetEnumerator()
        {
            return this;
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return this;
        }
        #endregion

        public void Dispose()
        {
            // Nothing to dispose
        }
    }
}