[ExI] Happy numbers - lucky, mersenne, kaprekar, narcissistic, …

[BillK]

Rockstar numbers of math — lucky, mersenne, kaprekar, narcissistic,
self, abundant, deficient …
Erman Akdogan   Oct 18, 2022

<https://medium.com/predict/rockstar-numbers-of-math-lucky-mersenne-kaprekar-narcissistic-self-abundant-deficient-62829f9e9744>

Quote:
A number is special if it has a unique mathematical property that
makes it interesting or useful. There are many special numbers in
mathematics, including prime numbers, Fibonacci numbers, and Pi.
Let’s take a deeper look at some lesser known constants and special numbers:
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Interesting article - (to maths geeks).  :)
I've never heard of some of these unusual numbers......

BillK