References: Inder J. Taneja, Single Digits Representations of Numbers from 1 to 20000,  https://inderjtaneja.com/2019/01/01/single-letter-representations-of-numbers-from-1-to-20000/Inder J. Taneja, Single Letter Representations Of Natural Numbers, https://inderjtaneja.com/2017/08/19/single-letter-representations-of-natural-numbers/Crazy Representations of Natural Numbers – The 10958 ProblemCrazy Representations of Natural Numbers Using Factorial From 200001 to 300000Patterns in Single Letter Representations of Natural Numbers